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kageru/day8.nim

Created Dec 20, 2017
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Day 8 of the Advent of Code in nim (only the first part)
import tables
import nre
import strutils
let pattern = re"(?<target>\w+)\s(?<opcode>(inc|dec))\s(?<value>-?\d+)\sif\s(?<comptarget>\w+)\s(?<compop>(<|>|==|!=|<=|>=))\s(?<comp2>-?\d+)"
var registers = initTable[string, int]();
proc parseLine(li: string): RegexMatch =
let found = nre.find(li, pattern)
if found.isNone:
echo("mismatch")
return
return found.get()
proc compare(target: string, val2: int, op: string): bool =
# text parsing done right ヽ( ゚ヮ・)ノ
let val1 = registers[target]
case op
of "<":
return val1 < val2;
of ">":
return val1 > val2;
of "==":
return val1 == val2;
of "!=":
return val1 != val2;
of "<=":
return val1 <= val2;
of ">=":
return val1 >= val2;
else: discard
proc changeRegister(r: string, op: string, val: int): void =
# only ‘inc’ and ‘dec’ are possible
if op == "inc":
registers[r] += val
else:
registers[r] -= val
proc executeLine(ins: Table): void =
# set registers to 0 if they haven’t been initialized
if not registers.hasKey(ins["comptarget"]):
registers[ins["comptarget"]] = 0
if not registers.hasKey(ins["target"]):
registers[ins["target"]] = 0
# do math... or don’t
if compare(ins["comptarget"], parseInt(ins["comp2"]), ins["compop"]):
changeRegister(ins["target"], ins["opcode"], parseInt(ins["value"]))
for line in lines "day8.txt":
let parsed = parseLine(line)
executeLine(parsed.captures.toTable())
# returning a list like with python’s dict.values doesn’t seem to work.
# is there a way to convert iterables to arrays?
var maximum = 0
for v in values(registers):
if v > maximum:
maximum = v
echo(maximum)
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