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@@ -36,19 +36,38 @@ func readInput(file *os.File) [][]int {
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return reports
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}
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-func safe(report []int) bool {
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+func check(a, b int, direction int) (bool, int) {
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+ delta := b - a
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+ if delta == 0 || delta < -3 || delta > 3 {
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+ return false, direction
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+ }
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+
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+ if direction == 0 {
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+ direction = delta
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+ } else if direction < 0 && delta > 0 || direction > 0 && delta < 0 {
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+ return false, direction
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+ }
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+
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+ return true, direction
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+}
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+
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+func safe(report []int, skip bool) bool {
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var direction int
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+ var status bool
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edge := len(report)
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for i := 1; i < edge; i++ {
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- delta := report[i] - report[i-1]
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- if delta == 0 || delta < -3 || delta > 3 {
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- return false
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- }
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+ status, direction = check(report[i], report[i-1], direction)
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+ if !status {
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+ if skip && i+1 < edge {
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+ status, direction = check(report[i+1], report[i-1], direction)
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+ if status {
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+ i++
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+ skip = false
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+ continue
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+ }
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+ }
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- if direction == 0 {
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- direction = delta
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- } else if direction < 0 && delta > 0 || direction > 0 && delta < 0 {
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return false
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}
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}
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@@ -56,10 +75,10 @@ func safe(report []int) bool {
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return true
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}
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-func part1(reports [][]int) int {
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+func part(reports [][]int, skip bool) int {
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var result int
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for _, report := range reports {
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- if safe(report) {
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+ if safe(report, skip) {
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result++
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}
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}
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@@ -79,5 +98,6 @@ func main() {
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}
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reports := readInput(file)
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- fmt.Println("Part1:", part1(reports))
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+ fmt.Println("Part1:", part(reports, false))
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+ fmt.Println("Part2:", part(reports, true))
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}
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