initialise

5/main.go

@@ -0,0 +1,109 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"regexp"
+	"strconv"
+)
+
+func calcScore(s [][]string) int {
+  result := 0
+  for i := range s {
+    if len(s[i]) % 2 == 0 {
+      fmt.Println("The following valid update has an even length, so cannot calculate the middle page: ", s[i])
+    } else {
+      middle := (len(s[i]) + 1) / 2
+      middlePage, _ := strconv.Atoi(s[i][middle - 1])
+      result = result + middlePage
+    }
+  }
+  return result
+}
+
+func isValid(update []string, rules [][]string) bool {
+  valid := true
+  for i:=1; i<len(update); i++ { //FOR EACH NUMBER OF THE UPDATE
+    for j := range rules { //FOR EACH RULE
+      if update[i] != rules[j][0] {
+         continue
+      } else {
+        for k:=0; k<i; k++ { //FOR EACH
+          if update[k] == rules[j][1] {
+            valid = false
+            break
+          }
+        } 
+      }
+    }
+  }
+  return valid
+}
+
+func makeValid(update []string, rules [][]string) []string {
+  for i:=1; i<len(update); i++ { //FOR EACH NUMBER OF THE UPDATE
+    for j := range rules { //FOR EACH RULE
+      if update[i] != rules[j][0] {
+         continue
+      } else {
+        for k:=0; k<i; k++ { //FOR EACH
+          if update[k] == rules[j][1] {
+            temp := update[k]
+            update[k] = update[i]
+            update[i] = temp
+            break
+          }
+        } 
+      }
+    }
+  }
+  if ! isValid(update, rules) {
+    update=makeValid(update, rules)
+  }
+  return update
+}
+
+func main() {
+  file, _ := os.Open("input")
+  defer file.Close()
+  scanner := bufio.NewScanner(file)
+  ruleRegex := regexp.MustCompile(`[0-9]+\|[0-9]+`)
+  updateRegex := regexp.MustCompile(`^(\d+(,\d+)*)$`)
+  numberRegex := regexp.MustCompile(`[0-9]+`)
+  rules := [][]string{}
+  updates := [][]string{}
+  for scanner.Scan() {
+    line := scanner.Text()
+    ruleMatches := ruleRegex.FindAllString(line, -1)
+    updateMatches := updateRegex.FindAllString(line, -1)
+    rule := []string{}
+    update := []string{}    
+    for i := range ruleMatches {
+      rule = append(rule, numberRegex.FindAllString(ruleMatches[i], -1)...)
+    }
+    for i := range updateMatches {
+      update = append(update, numberRegex.FindAllString(updateMatches[i], -1)...)
+    }
+    if len(rule) > 0 {
+      rules = append(rules, rule)
+    }
+    if len(update) > 0 {
+      updates = append(updates, update)
+    }
+  }
+  validUpdates := [][]string{}
+  invalidUpdates := [][]string{}
+  for i := range updates {
+    if isValid(updates[i], rules) {
+      validUpdates = append(validUpdates, updates[i])
+    } else {
+      valid:=makeValid(updates[i], rules)
+      invalidUpdates = append(invalidUpdates, valid)
+    }
+  }
+  validScore := calcScore(validUpdates)
+  fmt.Println("Score of valid updates: ", validScore)
+  invalidScore := calcScore(invalidUpdates)
+  fmt.Println(invalidScore)
+}