98 lines
2.1 KiB
Go
98 lines
2.1 KiB
Go
package day_02
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import (
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"strconv"
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"strings"
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)
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// task:https://adventofcode.com/2024/day/2
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// short summary - find valid reports
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// reports are valid if:
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// 1. numbers are either all increasing or all decreasing
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// 2. two adjacent numbers differ by at least one and at most three.
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func SolveBasic(input string) int {
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reports := strings.Split(input, "\n")
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safeReports := 0
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for _, report := range reports {
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if isSafeReport(asInts(strings.Split(report, " "))) {
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safeReports++
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}
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}
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return safeReports
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}
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// task:https://adventofcode.com/2024/day/2#part2
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// short summary - find valid reports
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// same as above, reports are valid if:
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// 1. numbers are either all increasing or all decreasing
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// 2. two adjacent numbers differ by at least one and at most three.
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// BUT ALSO
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// 3. reports is valid if removing one number makes it safe
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func SolveComplex(input string) int {
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reports := strings.Split(input, "\n")
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safeReports := 0
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for _, report := range reports {
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levels := asInts(strings.Split(report, " "))
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if isSafeReport(levels) {
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safeReports++
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} else {
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reducedLevels := make([]int, len(levels)-1)
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for skipped := 0; skipped < len(levels); skipped++ {
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pos := 0
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for i := 0; i < len(levels); i++ {
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if i == skipped {
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continue
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}
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reducedLevels[pos] = levels[i]
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pos++
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}
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if isSafeReport(reducedLevels) {
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safeReports++
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break
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}
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}
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}
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}
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return safeReports
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}
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// helper methods
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func isSafeReport(levels []int) bool {
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if levels[0] == levels[1] {
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return false
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} else if levels[0] < levels[1] {
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for i := 0; i < len(levels)-1; i++ {
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diff := levels[i+1] - levels[i]
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if diff < 1 || diff > 3 {
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return false
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}
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}
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} else if levels[0] > levels[1] {
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for i := 0; i < len(levels)-1; i++ {
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diff := levels[i] - levels[i+1]
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if diff < 1 || diff > 3 {
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return false
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}
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}
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}
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return true
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}
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func asInts(numbers []string) []int {
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values := make([]int, 0, len(numbers))
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for _, v := range numbers {
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values = append(values, asInt(v))
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}
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return values
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}
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func asInt(v string) int {
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value, err := strconv.Atoi(v)
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if err != nil {
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panic(err)
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}
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return value
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}
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