Day 6

6/main.go

@@ -0,0 +1,72 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strings"
+)
+
+func main() {
+	type void struct{}
+	yes := void{}
+	group := map[rune]void{}
+	count := 0
+
+	newGroup := func() {
+		count += len(group)
+		group = map[rune]void{}
+	}
+
+	file, _ := os.Open("input.txt")
+	defer file.Close()
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		text := scanner.Text()
+		if len(text) == 0 {
+			// Empty row, new group
+			newGroup()
+		} else {
+			for _, r := range strings.ReplaceAll(text, " ", "") {
+				group[r] = yes
+			}
+		}
+	}
+	// Last group
+	newGroup()
+
+	fmt.Println("Part 1:", count)
+
+	// Part 2
+	count = 0
+	isNewGroup := true
+
+	file2, _ := os.Open("input.txt")
+	defer file2.Close()
+	scanner = bufio.NewScanner(file2)
+	for scanner.Scan() {
+		text := scanner.Text()
+		if len(text) == 0 {
+			// Empty row, new group
+			newGroup()
+			isNewGroup = true
+		} else {
+			if isNewGroup {
+				// First person
+				for _, r := range strings.ReplaceAll(text, " ", "") {
+					group[r] = yes
+				}
+				isNewGroup = false
+			} else {
+				for r := range group {
+					if !strings.ContainsRune(text, r) {
+						delete(group, r)
+					}
+				}
+			}
+		}
+	}
+	newGroup()
+
+	fmt.Println("Part 2:", count)
+}