2024: day 07. part 1. golang

Author: Tsovak

src/2024/day07/1/main.go

@@ -0,0 +1,71 @@
+package main
+
+import (
+	_ "embed"
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+//go:embed data.txt
+var fileContents string
+
+func evaluateExpression(numbers []int, ops []string) int {
+	result := numbers[0]
+	for i, op := range ops {
+		if op == "+" {
+			result += numbers[i+1]
+		} else {
+			result *= numbers[i+1]
+		}
+	}
+	return result
+}
+
+func findValidEquations(desiredSum int, numbers []int) [][]string {
+	var validEquations [][]string
+	allowedOperations := []string{"+", "*"}
+
+	// generate all possible operation combinations
+	var generateCombinations func(int, []string)
+	generateCombinations = func(depth int, current []string) {
+		if depth == len(numbers)-1 {
+			// try the current combination
+			result := evaluateExpression(numbers, current)
+			if result == desiredSum {
+				validEquations = append(validEquations, append([]string{}, current...))
+			}
+			return
+		}
+
+		for _, op := range allowedOperations {
+			generateCombinations(depth+1, append(current, op))
+		}
+	}
+
+	generateCombinations(0, []string{})
+	return validEquations
+}
+
+func main() {
+	lines := strings.Split(strings.TrimSpace(fileContents), "\n")
+
+	totalCalibration := 0
+	for _, line := range lines {
+		parts := strings.Split(line, ": ")
+		desiredSum, _ := strconv.Atoi(parts[0])
+
+		numberStrs := strings.Fields(parts[1])
+		numbers := make([]int, len(numberStrs))
+		for i, numStr := range numberStrs {
+			numbers[i], _ = strconv.Atoi(numStr)
+		}
+
+		validEquations := findValidEquations(desiredSum, numbers)
+		if len(validEquations) > 0 {
+			totalCalibration += desiredSum
+		}
+	}
+
+	fmt.Println(totalCalibration)
+}