git.scottworley.com Git - planeteer/blob - planeteer.go

   1 /* Planeteer: Give trade route advice for Planets: The Exploration of Space
   2  * Copyright (C) 2011  Scott Worley <sworley@chkno.net>
   3  *
   4  * This program is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU Affero General Public License as
   6  * published by the Free Software Foundation, either version 3 of the
   7  * License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU Affero General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Affero General Public License
  15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 package main
  19
  20 import "flag"
  21 import "fmt"
  22 import "json"
  23 import "os"
  24 import "runtime/pprof"
  25 import "strings"
  26
  27 var funds = flag.Int("funds", 0,
  28         "Starting funds")
  29
  30 var start = flag.String("start", "",
  31         "The planet to start at")
  32
  33 var flight_plan_string = flag.String("flight_plan", "",
  34         "Your hyper-holes for the day, comma-separated.")
  35
  36 var end_string = flag.String("end", "",
  37         "A comma-separated list of acceptable ending planets.")
  38
  39 var planet_data_file = flag.String("planet_data_file", "planet-data",
  40         "The file to read planet data from")
  41
  42 var fuel = flag.Int("fuel", 16, "Hyper Jump power left")
  43
  44 var hold = flag.Int("hold", 300, "Size of your cargo hold")
  45
  46 var start_edens = flag.Int("start_edens", 0,
  47         "How many Eden Warp Units are you starting with?")
  48
  49 var end_edens = flag.Int("end_edens", 0,
  50         "How many Eden Warp Units would you like to keep (not use)?")
  51
  52 var cloak = flag.Bool("cloak", false,
  53         "Make sure to end with a Device of Cloaking")
  54
  55 var drones = flag.Int("drones", 0, "Buy this many Fighter Drones")
  56
  57 var batteries = flag.Int("batteries", 0, "Buy this many Shield Batterys")
  58
  59 var drone_price = flag.Int("drone_price", 0, "Today's Fighter Drone price")
  60
  61 var battery_price = flag.Int("battery_price", 0, "Today's Shield Battery price")
  62
  63 var visit_string = flag.String("visit", "",
  64         "A comma-separated list of planets to make sure to visit")
  65
  66 var cpuprofile = flag.String("cpuprofile", "", "write cpu profile to file")
  67
  68 var visit_cache []string
  69
  70 func visit() []string {
  71         if visit_cache == nil {
  72                 if *visit_string == "" {
  73                         return nil
  74                 }
  75                 visit_cache = strings.Split(*visit_string, ",")
  76         }
  77         return visit_cache
  78 }
  79
  80 var flight_plan_cache []string
  81
  82 func flight_plan() []string {
  83         if flight_plan_cache == nil {
  84                 if *flight_plan_string == "" {
  85                         return nil
  86                 }
  87                 flight_plan_cache = strings.Split(*flight_plan_string, ",")
  88         }
  89         return flight_plan_cache
  90 }
  91
  92 var end_cache map[string]bool
  93
  94 func end() map[string]bool {
  95         if end_cache == nil {
  96                 if *end_string == "" {
  97                         return nil
  98                 }
  99                 m := make(map[string]bool)
 100                 for _, p := range strings.Split(*end_string, ",") {
 101                         m[p] = true
 102                 }
 103                 end_cache = m
 104         }
 105         return end_cache
 106 }
 107
 108 type Commodity struct {
 109         BasePrice int
 110         CanSell   bool
 111         Limit     int
 112 }
 113 type Planet struct {
 114         BeaconOn bool
 115         Private  bool
 116         /* Use relative prices rather than absolute prices because you
 117            can get relative prices without traveling to each planet. */
 118         RelativePrices map[string]int
 119 }
 120 type planet_data struct {
 121         Commodities map[string]Commodity
 122         Planets     map[string]Planet
 123         p2i, c2i    map[string]int // Generated; not read from file
 124         i2p, i2c    []string       // Generated; not read from file
 125 }
 126
 127 func ReadData() (data planet_data) {
 128         f, err := os.Open(*planet_data_file)
 129         if err != nil {
 130                 panic(err)
 131         }
 132         defer f.Close()
 133         err = json.NewDecoder(f).Decode(&data)
 134         if err != nil {
 135                 panic(err)
 136         }
 137         return
 138 }
 139
 140 /* This program operates by filling in a state table representing the best
 141  * possible trips you could make; the ones that makes you the most money.
 142  * This is feasible because we don't look at all the possible trips.
 143  * We define a list of things that are germane to this game and then only
 144  * consider the best outcome in each possible game state.
 145  *
 146  * Each cell in the table represents a state in the game.  In each cell,
 147  * we track two things: 1. the most money you could possibly have while in
 148  * that state and 2. one possible way to get into that state with that
 149  * amount of money.
 150  *
 151  * A basic analysis can be done with a two-dimensional table: location and
 152  * fuel.  planeteer-1.0 used this two-dimensional table.  This version
 153  * adds features mostly by adding dimensions to this table.
 154  *
 155  * Note that the sizes of each dimension are data driven.  Many dimensions
 156  * collapse to one possible value (ie, disappear) if the corresponding
 157  * feature is not enabled.
 158  *
 159  * The order of the dimensions in the list of constants below determines
 160  * their layout in RAM.  The cargo-based 'dimensions' are not completely
 161  * independent -- some combinations are illegal and not used.  They are
 162  * handled as three dimensions rather than one for simplicity.  Placing
 163  * these dimensions first causes the unused cells in the table to be
 164  * grouped together in large blocks.  This keeps them from polluting
 165  * cache lines, and if they are large enough, allows the memory manager
 166  * to swap out entire pages.
 167  *
 168  * If the table gets too big to fit in RAM:
 169  *    * Combine the Edens, Cloaks, and UnusedCargo dimensions.  Of the
 170  *      24 combinations, only 15 are legal: a 38% savings.
 171  *    * Reduce the size of the Fuel dimension to 3.  We only ever look
 172  *      backwards 2 units, so just rotate the logical values through
 173  *      the same 3 physical addresses.  This is good for an 82% savings.
 174  *    * Reduce the size of the Edens dimension from 3 to 2, for the
 175  *      same reasons as Fuel above.  33% savings.
 176  *    * Buy more ram.  (Just sayin'.  It's cheaper than you think.)
 177  *
 178  */
 179
 180 // The official list of dimensions:
 181 const (
 182         // Name                Num   Size  Description
 183         Edens       = iota //   1      3  # of Eden warp units (0 - 2 typically)
 184         Cloaks             //   2    1-2  # of Devices of Cloaking (0 or 1)
 185         UnusedCargo        //   3      4  # of unused cargo spaces (0 - 3 typically)
 186         Fuel               //   4     17  Hyper jump power left (0 - 16)
 187         Location           //   5     26  Location (which planet)
 188         Hold               //   6     15  Cargo bay contents (a *Commodity or nil)
 189         Traded             //   7      2  Traded yet?
 190         BuyFighters        //   8    1-2  Errand: Buy fighter drones
 191         BuyShields         //   9    1-2  Errand: Buy shield batteries
 192         Visit              //  10 1-2**N  Visit: Stop by these N planets in the route
 193
 194         NumDimensions
 195 )
 196
 197 func bint(b bool) int {
 198         if b {
 199                 return 1
 200         }
 201         return 0
 202 }
 203
 204 func DimensionSizes(data planet_data) []int {
 205         eden_capacity := data.Commodities["Eden Warp Units"].Limit
 206         if *start_edens > eden_capacity {
 207                 eden_capacity = *start_edens
 208         }
 209         cloak_capacity := bint(*cloak)
 210         dims := make([]int, NumDimensions)
 211         dims[Edens] = eden_capacity + 1
 212         dims[Cloaks] = cloak_capacity + 1
 213         dims[UnusedCargo] = eden_capacity + cloak_capacity + 1
 214         dims[Fuel] = *fuel + 1
 215         dims[Location] = len(data.Planets)
 216         dims[Hold] = len(data.Commodities) + 1
 217         dims[Traded] = 2
 218         dims[BuyFighters] = bint(*drones > 0) + 1
 219         dims[BuyShields] = bint(*batteries > 0) + 1
 220         dims[Visit] = 1 << uint(len(visit()))
 221
 222         // Remind myself to add a line above when adding new dimensions
 223         for i, dim := range dims {
 224                 if dim < 1 {
 225                         panic(i)
 226                 }
 227         }
 228         return dims
 229 }
 230
 231 func StateTableSize(dims []int) int {
 232         product := 1
 233         for _, size := range dims {
 234                 product *= size
 235         }
 236         return product
 237 }
 238
 239 type State struct {
 240         value, from int32
 241 }
 242
 243 const (
 244         CELL_UNINITIALIZED = -2147483647 + iota
 245         CELL_BEING_EVALUATED
 246         CELL_RUBISH
 247 )
 248
 249 func EncodeIndex(dims, addr []int) int32 {
 250         index := addr[0]
 251         if addr[0] > dims[0] {
 252                 panic(0)
 253         }
 254         for i := 1; i < NumDimensions; i++ {
 255                 if addr[i] < 0 || addr[i] >= dims[i] {
 256                         panic(i)
 257                 }
 258                 index = index*dims[i] + addr[i]
 259         }
 260         return int32(index)
 261 }
 262
 263 func DecodeIndex(dims []int, index int32) []int {
 264         addr := make([]int, NumDimensions)
 265         for i := NumDimensions - 1; i > 0; i-- {
 266                 addr[i] = int(index) % dims[i]
 267                 index /= int32(dims[i])
 268         }
 269         addr[0] = int(index)
 270         return addr
 271 }
 272
 273 func CreateStateTable(data planet_data, dims []int) []State {
 274         table := make([]State, StateTableSize(dims))
 275         for i := range table {
 276                 table[i].value = CELL_UNINITIALIZED
 277         }
 278
 279         addr := make([]int, NumDimensions)
 280         addr[Fuel] = *fuel
 281         addr[Edens] = *start_edens
 282         addr[Location] = data.p2i[*start]
 283         addr[Traded] = 1
 284         table[EncodeIndex(dims, addr)].value = int32(*funds)
 285
 286         return table
 287 }
 288
 289 /* CellValue fills in the one cell at address addr by looking at all
 290  * the possible ways to reach this cell and selecting the best one. */
 291
 292 func Consider(data planet_data, dims []int, table []State, there []int, value_difference int, best_value *int32, best_source []int) {
 293         there_value := CellValue(data, dims, table, there)
 294         if value_difference < 0 && int32(-value_difference) > there_value {
 295                 /* Can't afford this transition */
 296                 return
 297         }
 298         possible_value := there_value + int32(value_difference)
 299         if possible_value > *best_value {
 300                 *best_value = possible_value
 301                 copy(best_source, there)
 302         }
 303 }
 304
 305 var cell_filled_count int
 306
 307 func CellValue(data planet_data, dims []int, table []State, addr []int) int32 {
 308         my_index := EncodeIndex(dims, addr)
 309         if table[my_index].value == CELL_BEING_EVALUATED {
 310                 panic("Circular dependency")
 311         }
 312         if table[my_index].value != CELL_UNINITIALIZED {
 313                 return table[my_index].value
 314         }
 315         table[my_index].value = CELL_BEING_EVALUATED
 316
 317         best_value := int32(CELL_RUBISH)
 318         best_source := make([]int, NumDimensions)
 319         other := make([]int, NumDimensions)
 320         copy(other, addr)
 321         planet := data.i2p[addr[Location]]
 322
 323         /* Travel here */
 324         if addr[Traded] == 0 { /* Can't have traded immediately after traveling. */
 325                 other[Traded] = 1 /* Travel from states that have done trading. */
 326
 327                 /* Travel here via a 2-fuel unit jump */
 328                 if addr[Fuel]+2 < dims[Fuel] {
 329                         other[Fuel] = addr[Fuel] + 2
 330                         hole_index := (dims[Fuel] - 1) - (addr[Fuel] + 2)
 331                         if hole_index >= len(flight_plan()) || addr[Location] != data.p2i[flight_plan()[hole_index]] {
 332                                 for other[Location] = 0; other[Location] < dims[Location]; other[Location]++ {
 333                                         if data.Planets[data.i2p[addr[Location]]].BeaconOn {
 334                                                 Consider(data, dims, table, other, 0, &best_value, best_source)
 335                                         }
 336                                 }
 337                         }
 338                         other[Location] = addr[Location]
 339                         other[Fuel] = addr[Fuel]
 340                 }
 341
 342                 /* Travel here via a 1-fuel unit jump (a hyper hole) */
 343                 if addr[Fuel]+1 < dims[Fuel] {
 344                         hole_index := (dims[Fuel] - 1) - (addr[Fuel] + 1)
 345                         if hole_index < len(flight_plan()) && addr[Location] == data.p2i[flight_plan()[hole_index]] {
 346                                 other[Fuel] = addr[Fuel] + 1
 347                                 for other[Location] = 0; other[Location] < dims[Location]; other[Location]++ {
 348                                         Consider(data, dims, table, other, 0, &best_value, best_source)
 349                                 }
 350                                 other[Location] = addr[Location]
 351                                 other[Fuel] = addr[Fuel]
 352                         }
 353                 }
 354
 355                 /* Travel here via Eden Warp Unit */
 356                 if addr[Edens]+1 < dims[Edens] && addr[UnusedCargo] > 0 {
 357                         _, available := data.Planets[data.i2p[addr[Location]]].RelativePrices["Eden Warp Units"]
 358                         if !available {
 359                                 other[Edens] = addr[Edens] + 1
 360                                 if other[Hold] != 0 {
 361                                         other[UnusedCargo] = addr[UnusedCargo] - 1
 362                                 }
 363                                 for other[Location] = 0; other[Location] < dims[Location]; other[Location]++ {
 364                                         Consider(data, dims, table, other, 0, &best_value, best_source)
 365                                 }
 366                                 other[Location] = addr[Location]
 367                                 other[UnusedCargo] = addr[UnusedCargo]
 368                                 other[Edens] = addr[Edens]
 369                         }
 370                 }
 371                 other[Traded] = addr[Traded]
 372         }
 373
 374         /* Trade */
 375         if addr[Traded] == 1 {
 376                 other[Traded] = 0
 377
 378                 /* Consider not trading */
 379                 Consider(data, dims, table, other, 0, &best_value, best_source)
 380
 381                 if !data.Planets[data.i2p[addr[Location]]].Private {
 382
 383                         /* Sell */
 384                         if addr[Hold] == 0 && addr[UnusedCargo] == 0 {
 385                                 for other[Hold] = 0; other[Hold] < dims[Hold]; other[Hold]++ {
 386                                         commodity := data.i2c[other[Hold]]
 387                                         if !data.Commodities[commodity].CanSell {
 388                                                 continue
 389                                         }
 390                                         relative_price, available := data.Planets[planet].RelativePrices[commodity]
 391                                         if !available {
 392                                                 // TODO: Dump cargo
 393                                                 continue
 394                                         }
 395                                         base_price := data.Commodities[commodity].BasePrice
 396                                         absolute_price := float64(base_price) * float64(relative_price) / 100.0
 397                                         sell_price := int(absolute_price * 0.9)
 398
 399                                         for other[UnusedCargo] = 0; other[UnusedCargo] < dims[UnusedCargo]; other[UnusedCargo]++ {
 400                                                 quantity := *hold - (other[UnusedCargo] + other[Cloaks] + other[Edens])
 401                                                 sale_value := quantity * sell_price
 402                                                 Consider(data, dims, table, other, sale_value, &best_value, best_source)
 403                                         }
 404                                 }
 405                                 other[UnusedCargo] = addr[UnusedCargo]
 406                                 other[Hold] = addr[Hold]
 407                         }
 408
 409                         /* Buy */
 410                         other[Traded] = addr[Traded] /* Buy after selling */
 411                         if addr[Hold] != 0 {
 412                                 commodity := data.i2c[addr[Hold]]
 413                                 if data.Commodities[commodity].CanSell {
 414                                         relative_price, available := data.Planets[planet].RelativePrices[commodity]
 415                                         if available {
 416                                                 base_price := data.Commodities[commodity].BasePrice
 417                                                 absolute_price := int(float64(base_price) * float64(relative_price) / 100.0)
 418                                                 quantity := *hold - (addr[UnusedCargo] + addr[Cloaks] + addr[Edens])
 419                                                 total_price := quantity * absolute_price
 420                                                 other[Hold] = 0
 421                                                 other[UnusedCargo] = 0
 422                                                 Consider(data, dims, table, other, -total_price, &best_value, best_source)
 423                                                 other[UnusedCargo] = addr[UnusedCargo]
 424                                                 other[Hold] = addr[Hold]
 425                                         }
 426                                 }
 427                         }
 428                 }
 429                 other[Traded] = addr[Traded]
 430         }
 431
 432         /* Buy a Device of Cloaking */
 433         if addr[Cloaks] == 1 && addr[UnusedCargo] < dims[UnusedCargo]-1 {
 434                 relative_price, available := data.Planets[data.i2p[addr[Location]]].RelativePrices["Device Of Cloakings"]
 435                 if available {
 436                         absolute_price := int(float64(data.Commodities["Device Of Cloakings"].BasePrice) * float64(relative_price) / 100.0)
 437                         other[Cloaks] = 0
 438                         if other[Hold] != 0 {
 439                                 other[UnusedCargo] = addr[UnusedCargo] + 1
 440                         }
 441                         Consider(data, dims, table, other, -absolute_price, &best_value, best_source)
 442                         other[UnusedCargo] = addr[UnusedCargo]
 443                         other[Cloaks] = addr[Cloaks]
 444                 }
 445         }
 446
 447         /* Buy Fighter Drones */
 448         if addr[BuyFighters] == 1 {
 449                 relative_price, available := data.Planets[data.i2p[addr[Location]]].RelativePrices["Fighter Drones"]
 450                 if available {
 451                         absolute_price := int(float64(data.Commodities["Fighter Drones"].BasePrice) * float64(relative_price) / 100.0)
 452                         other[BuyFighters] = 0
 453                         Consider(data, dims, table, other, -absolute_price**drones, &best_value, best_source)
 454                         other[BuyFighters] = addr[BuyFighters]
 455                 }
 456         }
 457
 458         /* Buy Shield Batteries */
 459         if addr[BuyShields] == 1 {
 460                 relative_price, available := data.Planets[data.i2p[addr[Location]]].RelativePrices["Shield Batterys"]
 461                 if available {
 462                         absolute_price := int(float64(data.Commodities["Shield Batterys"].BasePrice) * float64(relative_price) / 100.0)
 463                         other[BuyShields] = 0
 464                         Consider(data, dims, table, other, -absolute_price**batteries, &best_value, best_source)
 465                         other[BuyShields] = addr[BuyShields]
 466                 }
 467         }
 468
 469         /* Visit this planet */
 470         var i uint
 471         for i = 0; i < uint(len(visit())); i++ {
 472                 if addr[Visit]&(1<<i) != 0 && visit()[i] == data.i2p[addr[Location]] {
 473                         other[Visit] = addr[Visit] & ^(1 << i)
 474                         Consider(data, dims, table, other, 0, &best_value, best_source)
 475                 }
 476         }
 477         other[Visit] = addr[Visit]
 478
 479         /* Buy Eden warp units */
 480         eden_limit := data.Commodities["Eden Warp Units"].Limit
 481         if addr[Edens] > 0 && addr[Edens] <= eden_limit {
 482                 relative_price, available := data.Planets[data.i2p[addr[Location]]].RelativePrices["Eden Warp Units"]
 483                 if available {
 484                         absolute_price := int(float64(data.Commodities["Eden Warp Units"].BasePrice) * float64(relative_price) / 100.0)
 485                         for quantity := addr[Edens]; quantity > 0; quantity-- {
 486                                 other[Edens] = addr[Edens] - quantity
 487                                 if addr[Hold] != 0 {
 488                                         other[UnusedCargo] = addr[UnusedCargo] + quantity
 489                                 }
 490                                 if other[UnusedCargo] < dims[UnusedCargo] {
 491                                         Consider(data, dims, table, other, -absolute_price*quantity, &best_value, best_source)
 492                                 }
 493                         }
 494                         other[Edens] = addr[Edens]
 495                         other[UnusedCargo] = addr[UnusedCargo]
 496                 }
 497         }
 498
 499         // Check that we didn't lose track of any temporary modifications to other.
 500         for i := 0; i < NumDimensions; i++ {
 501                 if addr[i] != other[i] {
 502                         panic(i)
 503                 }
 504         }
 505
 506         // Sanity check: This cell was in state BEING_EVALUATED
 507         // the whole time that it was being evaluated.
 508         if table[my_index].value != CELL_BEING_EVALUATED {
 509                 panic(my_index)
 510         }
 511
 512         // Record our findings
 513         table[my_index].value = best_value
 514         table[my_index].from = EncodeIndex(dims, best_source)
 515
 516         // UI: Progress bar
 517         cell_filled_count++
 518         if cell_filled_count&0xff == 0 {
 519                 print(fmt.Sprintf("\r%3.1f%%", 100*float64(cell_filled_count)/float64(StateTableSize(dims))))
 520         }
 521
 522         return table[my_index].value
 523 }
 524
 525 func FindBestState(data planet_data, dims []int, table []State) int32 {
 526         addr := make([]int, NumDimensions)
 527         addr[Edens] = *end_edens
 528         addr[Cloaks] = dims[Cloaks] - 1
 529         addr[BuyFighters] = dims[BuyFighters] - 1
 530         addr[BuyShields] = dims[BuyShields] - 1
 531         addr[Visit] = dims[Visit] - 1
 532         addr[Traded] = 1
 533         addr[Hold] = 0
 534         addr[UnusedCargo] = 0
 535         max_index := int32(-1)
 536         max_value := int32(0)
 537         max_fuel := 1
 538         if *fuel == 0 {
 539                 max_fuel = 0
 540         }
 541         for addr[Fuel] = 0; addr[Fuel] <= max_fuel; addr[Fuel]++ {
 542                 for addr[Location] = 0; addr[Location] < dims[Location]; addr[Location]++ {
 543                         if len(end()) == 0 || end()[data.i2p[addr[Location]]] {
 544                                 index := EncodeIndex(dims, addr)
 545                                 value := CellValue(data, dims, table, addr)
 546                                 if value > max_value {
 547                                         max_value = value
 548                                         max_index = index
 549                                 }
 550                         }
 551                 }
 552         }
 553         return max_index
 554 }
 555
 556 func Commas(n int32) (s string) {
 557         r := n % 1000
 558         n /= 1000
 559         for n > 0 {
 560                 s = fmt.Sprintf(",%03d", r) + s
 561                 r = n % 1000
 562                 n /= 1000
 563         }
 564         s = fmt.Sprint(r) + s
 565         return
 566 }
 567
 568 func DescribePath(data planet_data, dims []int, table []State, start int32) (description []string) {
 569         for index := start; index > 0 && table[index].from > 0; index = table[index].from {
 570                 var line string
 571                 addr := DecodeIndex(dims, index)
 572                 prev := DecodeIndex(dims, table[index].from)
 573                 if addr[Fuel] != prev[Fuel] {
 574                         from := data.i2p[prev[Location]]
 575                         to := data.i2p[addr[Location]]
 576                         line += fmt.Sprintf("Jump from %v to %v (%v hyper jump units)", from, to, prev[Fuel]-addr[Fuel])
 577                 }
 578                 if addr[Edens] == prev[Edens]-1 {
 579                         from := data.i2p[prev[Location]]
 580                         to := data.i2p[addr[Location]]
 581                         line += fmt.Sprintf("Eden warp from %v to %v", from, to)
 582                 }
 583                 if addr[Hold] != prev[Hold] {
 584                         if addr[Hold] == 0 {
 585                                 quantity := *hold - (prev[UnusedCargo] + prev[Edens] + prev[Cloaks])
 586                                 line += fmt.Sprintf("Sell %v %v", quantity, data.i2c[prev[Hold]])
 587                         } else if prev[Hold] == 0 {
 588                                 quantity := *hold - (addr[UnusedCargo] + addr[Edens] + addr[Cloaks])
 589                                 line += fmt.Sprintf("Buy %v %v", quantity, data.i2c[addr[Hold]])
 590                         } else {
 591                                 panic("Switched cargo?")
 592                         }
 593
 594                 }
 595                 if addr[Cloaks] == 1 && prev[Cloaks] == 0 {
 596                         // TODO: Dump cloaks, convert from cargo?
 597                         line += "Buy a Cloak"
 598                 }
 599                 if addr[Edens] > prev[Edens] {
 600                         line += fmt.Sprint("Buy ", addr[Edens]-prev[Edens], " Eden Warp Units")
 601                 }
 602                 if addr[BuyShields] == 1 && prev[BuyShields] == 0 {
 603                         line += fmt.Sprint("Buy ", *batteries, " Shield Batterys")
 604                 }
 605                 if addr[BuyFighters] == 1 && prev[BuyFighters] == 0 {
 606                         line += fmt.Sprint("Buy ", *drones, " Fighter Drones")
 607                 }
 608                 if addr[Visit] != prev[Visit] {
 609                         // TODO: verify that the bit chat changed is addr[Location]
 610                         line += fmt.Sprint("Visit ", data.i2p[addr[Location]])
 611                 }
 612                 if line == "" && addr[Hold] == prev[Hold] && addr[Traded] != prev[Traded] {
 613                         // The Traded dimension is for housekeeping.  It doesn't directly
 614                         // correspond to in-game actions, so don't report transitions.
 615                         continue
 616                 }
 617                 if line == "" {
 618                         line = fmt.Sprint(prev, " -> ", addr)
 619                 }
 620                 description = append(description, fmt.Sprintf("%13v ", Commas(table[index].value))+line)
 621         }
 622         return
 623 }
 624
 625 // (Example of a use case for generics in Go)
 626 func IndexPlanets(m *map[string]Planet, start_at int) (map[string]int, []string) {
 627         e2i := make(map[string]int, len(*m)+start_at)
 628         i2e := make([]string, len(*m)+start_at)
 629         i := start_at
 630         for e := range *m {
 631                 e2i[e] = i
 632                 i2e[i] = e
 633                 i++
 634         }
 635         return e2i, i2e
 636 }
 637 func IndexCommodities(m *map[string]Commodity, start_at int) (map[string]int, []string) {
 638         e2i := make(map[string]int, len(*m)+start_at)
 639         i2e := make([]string, len(*m)+start_at)
 640         i := start_at
 641         for e := range *m {
 642                 e2i[e] = i
 643                 i2e[i] = e
 644                 i++
 645         }
 646         return e2i, i2e
 647 }
 648
 649 func main() {
 650         flag.Parse()
 651         if *start == "" || *funds == 0 {
 652                 print("--start and --funds are required.  --help for more\n")
 653                 return
 654         }
 655         if *cpuprofile != "" {
 656                 f, err := os.Create(*cpuprofile)
 657                 if err != nil {
 658                         panic(err)
 659                 }
 660                 pprof.StartCPUProfile(f)
 661                 defer pprof.StopCPUProfile()
 662         }
 663         data := ReadData()
 664         if *drone_price > 0 {
 665                 temp := data.Commodities["Fighter Drones"]
 666                 temp.BasePrice = *drone_price
 667                 data.Commodities["Fighter Drones"] = temp
 668         }
 669         if *battery_price > 0 {
 670                 temp := data.Commodities["Shield Batterys"]
 671                 temp.BasePrice = *battery_price
 672                 data.Commodities["Shield Batterys"] = temp
 673         }
 674         data.p2i, data.i2p = IndexPlanets(&data.Planets, 0)
 675         data.c2i, data.i2c = IndexCommodities(&data.Commodities, 1)
 676         dims := DimensionSizes(data)
 677         table := CreateStateTable(data, dims)
 678         best := FindBestState(data, dims, table)
 679         print("\n")
 680         if best == -1 {
 681                 print("Cannot acheive success criteria\n")
 682         } else {
 683                 description := DescribePath(data, dims, table, best)
 684                 for i := len(description) - 1; i >= 0; i-- {
 685                         fmt.Println(description[i])
 686                 }
 687         }
 688 }