110 lines
2.7 KiB
Go
110 lines
2.7 KiB
Go
package main
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import (
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"bufio"
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"fmt"
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"os"
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"regexp"
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"strconv"
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)
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func calcScore(s [][]string) int {
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result := 0
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for i := range s {
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if len(s[i]) % 2 == 0 {
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fmt.Println("The following valid update has an even length, so cannot calculate the middle page: ", s[i])
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} else {
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middle := (len(s[i]) + 1) / 2
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middlePage, _ := strconv.Atoi(s[i][middle - 1])
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result = result + middlePage
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}
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}
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return result
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}
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func isValid(update []string, rules [][]string) bool {
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valid := true
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for i:=1; i<len(update); i++ { //FOR EACH NUMBER OF THE UPDATE
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for j := range rules { //FOR EACH RULE
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if update[i] != rules[j][0] {
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continue
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} else {
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for k:=0; k<i; k++ { //FOR EACH
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if update[k] == rules[j][1] {
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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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}
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}
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return valid
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}
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func makeValid(update []string, rules [][]string) []string {
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for i:=1; i<len(update); i++ { //FOR EACH NUMBER OF THE UPDATE
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for j := range rules { //FOR EACH RULE
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if update[i] != rules[j][0] {
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continue
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} else {
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for k:=0; k<i; k++ { //FOR EACH
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if update[k] == rules[j][1] {
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temp := update[k]
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update[k] = update[i]
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update[i] = temp
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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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}
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if ! isValid(update, rules) {
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update=makeValid(update, rules)
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}
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return update
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}
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func main() {
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file, _ := os.Open("input")
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defer file.Close()
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scanner := bufio.NewScanner(file)
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ruleRegex := regexp.MustCompile(`[0-9]+\|[0-9]+`)
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updateRegex := regexp.MustCompile(`^(\d+(,\d+)*)$`)
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numberRegex := regexp.MustCompile(`[0-9]+`)
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rules := [][]string{}
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updates := [][]string{}
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for scanner.Scan() {
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line := scanner.Text()
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ruleMatches := ruleRegex.FindAllString(line, -1)
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updateMatches := updateRegex.FindAllString(line, -1)
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rule := []string{}
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update := []string{}
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for i := range ruleMatches {
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rule = append(rule, numberRegex.FindAllString(ruleMatches[i], -1)...)
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}
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for i := range updateMatches {
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update = append(update, numberRegex.FindAllString(updateMatches[i], -1)...)
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}
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if len(rule) > 0 {
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rules = append(rules, rule)
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}
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if len(update) > 0 {
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updates = append(updates, update)
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}
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}
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validUpdates := [][]string{}
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invalidUpdates := [][]string{}
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for i := range updates {
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if isValid(updates[i], rules) {
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validUpdates = append(validUpdates, updates[i])
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} else {
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valid:=makeValid(updates[i], rules)
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invalidUpdates = append(invalidUpdates, valid)
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}
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}
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validScore := calcScore(validUpdates)
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fmt.Println("Score of valid updates: ", validScore)
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invalidScore := calcScore(invalidUpdates)
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fmt.Println(invalidScore)
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}
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