101 lines
2.2 KiB
Go
101 lines
2.2 KiB
Go
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package main
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import (
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"fmt"
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"os"
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"strings"
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"strconv"
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)
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func check(e error) {
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if e != nil { panic(e) }
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}
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func contains(slice []int, element int) bool {
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for _, value := range slice {
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if value == element {
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return true
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}
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}
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return false
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}
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func get_prerequisites(rules [][2]int, target int) []int {
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out := make([]int, 0, 10)
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// find rules
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for _, rule := range rules {
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if rule[1] == target && !contains(out, rule[0]) {
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out = append(out, rule[0])
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}
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}
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return out
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}
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func main() {
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dat, err := os.ReadFile("data.txt")
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check(err)
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dat_str := string(dat[:len(dat) - 1])
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blocks := strings.Split(dat_str, "\n\n")
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rules := make([][2]int, 0, 1000)
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for _, rule := range strings.Split(blocks[0], "\n") {
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str_rules := strings.Split(rule, "|")
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num1, err := strconv.Atoi(str_rules[0])
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check(err)
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num2, err := strconv.Atoi(str_rules[1])
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check(err)
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rules = append(rules, [2]int{ num1, num2 })
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}
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orderings := make([][]int, 0, 1000)
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for _, line := range strings.Split(blocks[1], "\n") {
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str_orderings := strings.Split(line, ",")
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elements := make([]int, 0, len(str_orderings))
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for _, elem := range str_orderings {
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num, err := strconv.Atoi(elem)
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check(err)
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elements = append(elements, num)
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}
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orderings = append(orderings, elements)
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}
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// check orderings
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acc := 0
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var pre []int
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for _, ordering := range orderings {
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// check single line
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valid := true
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for i := len(ordering) - 1; i >= 0; i-- {
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pre = get_prerequisites(rules, ordering[i])
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for _, p := range pre {
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if contains(ordering, p) {
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if !contains(ordering[:i], p) {
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valid = false
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break
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}
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}
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}
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if !valid { break }
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}
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// add middle elem to acc
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if valid {
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acc += ordering[len(ordering)/2]
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}
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}
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fmt.Println(acc)
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}
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