Solution 2024, day 7

Author: lucianoq

2024/7/Makefile

@@ -0,0 +1,19 @@
+input:
+	http "https://adventofcode.com/2024/day/7/input" "Cookie:session=${AOC_SESSION};" >input
+
+main1:
+	go build -o main1 main1.go common.go
+
+main2:
+	go build -o main2 main2.go common.go
+
+.PHONY: run1 run2 clean
+
+run1: main1 input
+	./main1 <input
+
+run2: main2 input
+	./main2 <input
+
+clean:
+	rm -f main1 main2 input

2024/7/common.go

@@ -0,0 +1,27 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+func main() {
+	sum := 0
+	for scanner := bufio.NewScanner(os.Stdin); scanner.Scan(); {
+		ff := strings.Split(scanner.Text(), ":")
+		left, _ := strconv.Atoi(ff[0])
+		right := []int{}
+		for _, v := range strings.Fields(ff[1]) {
+			n, _ := strconv.Atoi(v)
+			right = append(right, n)
+		}
+
+		if valid(left, right[0], right[1:]) {
+			sum += left
+		}
+	}
+	fmt.Println(sum)
+}

2024/7/main1.go

@@ -0,0 +1,13 @@
+package main
+
+func valid(goal, temp int, others []int) bool {
+	if len(others) == 0 {
+		return temp == goal
+	}
+
+	if valid(goal, temp+others[0], others[1:]) {
+		return true
+	}
+
+	return valid(goal, temp*others[0], others[1:])
+}

2024/7/main2.go

@@ -0,0 +1,19 @@
+package main
+
+import "strconv"
+
+func valid(goal, temp int, others []int) bool {
+	if len(others) == 0 {
+		return temp == goal
+	}
+
+	if valid(goal, temp+others[0], others[1:]) {
+		return true
+	}
+	if valid(goal, temp*others[0], others[1:]) {
+		return true
+	}
+
+	temp, _ = strconv.Atoi(strconv.Itoa(temp) + strconv.Itoa(others[0]))
+	return valid(goal, temp, others[1:])
+}