90 lines
2.2 KiB
Nim
90 lines
2.2 KiB
Nim
import std/[strutils, sequtils, math]
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import aoc
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proc parseInstruction(i: string): (int, int) =
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let s = i.split(',')
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assert s.len == 2
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result = (parseInt(s[0]), parseInt(s[1]))
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proc parseInput(input: string): seq[(int, int)] =
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var i: int
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while i < input.len:
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case input[i]
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of 'm':
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# ul(x,y)
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# not enough space so bail
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if i > (input.len - 6): return
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else:
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var instruction: string
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if input[i .. i+3] == "mul(":
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i += 4
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while true:
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let c = input[i]
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case c:
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of '0'..'9':
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instruction.add c; inc i
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of ')':
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result.add parseInstruction instruction
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break
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of ',':
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instruction.add c; inc i
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else: break
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inc i
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else: inc i
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proc partOne*(input: string): int =
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let instructions = parseInput(input)
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instructions.mapIt(it[0] * it[1]).sum()
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proc parseInput2(input: string): seq[(int, int)] =
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var i: int
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var working = true
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while i < input.len:
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case input[i]
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of 'd':
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# check for enough room for don't()
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if i > (input.len - 6): inc i
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else:
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if input[i .. i + 3] == "do()":
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working = true
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i += 3
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elif input[i .. i + 6] == "don't()":
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working = false
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i += 6
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inc i
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of 'm':
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# ul(x,y)
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# not enough space for instruction so bail
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if i > (input.len - 6): return
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else:
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var instruction: string
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if input[i .. i+3] == "mul(":
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i += 4
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while true:
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let c = input[i]
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case c:
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of '0'..'9':
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instruction.add c; inc i
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of ')':
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if working:
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result.add parseInstruction instruction
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break
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of ',':
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instruction.add c; inc i
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else: break
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inc i
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else: inc i
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proc partTwo*(input: string): int =
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let instructions = parseInput2(input)
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instructions.mapIt(it[0] * it[1]).sum()
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solve:
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"example.txt":
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partOne: 161
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"example2.txt":
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partTwo: 48
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"input.txt":
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partOne: 164730528
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partTwo: 70478672
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