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@@ -51,6 +51,27 @@ func part1(lefts, rights []int) int {
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return distance
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}
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+func part2(lefts, rights []int) int {
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+ onTheLeft := make(map[int]int)
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+ for _, left := range lefts {
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+ onTheLeft[left] = 0
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+ }
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+
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+ for _, right := range rights {
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+ _, ok := onTheLeft[right]
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+ if ok {
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+ onTheLeft[right]++
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+ }
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+ }
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+
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+ var result int
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+ for _, left := range lefts {
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+ result += left * onTheLeft[left]
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+ }
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+
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+ return result
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+}
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+
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func main() {
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if len(os.Args) < 2 {
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log.Fatal("You need to specify a file!")
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@@ -64,4 +85,5 @@ func main() {
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lefts, rights := readInput(file)
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fmt.Println("Part1:", part1(lefts, rights))
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+ fmt.Println("Part2:", part2(lefts, rights))
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}
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