54 lines
1.7 KiB
Nim
54 lines
1.7 KiB
Nim
import ./common, std/[sequtils, algorithm, sugar, sets, strformat, strutils, tables, options, json, hashes, random]
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const BOARD_POSITIONS = 10
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proc p1(input: Lines): uint64 =
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var scores = [0, 0]
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var pos = [input[0].split(": ")[1].parseInt - 1, input[1].split(": ")[1].parseInt - 1]
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var rollNum = 1
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var turn = 0
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while scores[0] < 1000 and scores[1] < 1000:
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var move = 0
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for _ in 1..3:
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move += rollNum mod 100
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inc rollNum
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pos[turn] = (pos[turn] + move) mod BOARD_POSITIONS
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scores[turn] += pos[turn] + 1
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turn = (turn + 1) mod 2
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uint64(scores[turn mod 2] * (rollNum - 1))
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type DiracGamestate = tuple
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scores: array[2, int]
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positions: array[2, int]
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turn: int
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var turnOutcomes = newTable[DiracGamestate, array[2, uint64]]()
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proc turn(g: DiracGamestate): array[2, uint64] =
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if turnOutcomes.hasKey g: return turnOutcomes[g]
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if g.scores[0] >= 21:
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return [1'u64, 0]
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elif g.scores[1] >= 21:
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return [0'u64, 1]
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for r in product(@[@[1,2,3],@[1,2,3],@[1,2,3]]):
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let move = r.foldl(a + b)
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var ng = g
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ng.positions[ng.turn] = (ng.positions[ng.turn] + move) mod BOARD_POSITIONS
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ng.scores[ng.turn] += ng.positions[ng.turn] + 1
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ng.turn = (ng.turn + 1) mod 2
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let r = turn(ng)
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turnOutcomes[ng] = r
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result[0] += r[0]
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result[1] += r[1]
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proc p2(input: Lines): uint64 =
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var pos = [input[0].split(": ")[1].parseInt - 1, input[1].split(": ")[1].parseInt - 1]
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var g: DiracGamestate = (scores: [0, 0], positions: pos, turn: 0)
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let wins = turn(g)
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wins.max
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const input = """
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Player 1 starting position: 4
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Player 2 starting position: 8
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""".strip().split('\n')
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doDayX 21, (n: int) => n.loadInput, p1, p2, (input, 739785'u64, 444356092776315'u64)
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