Day 3 Part 1

.gitignore

@@ -0,0 +1,4 @@
+*/input.txt
+*/dummy_input.txt
+*/Cargo.lock
+*/target/

README.md

@@ -3,5 +3,7 @@
 Este es mi intento para resolver todos¹ los problemas del [AOC 2025](https://adventofcode.com/).
 
 Día 1: Rust
+Día 2: Python
+Día 3: Go
 
 ¹ Ojalá

day-3/main.go

@@ -0,0 +1,45 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+func check(e error) {
+	if e != nil {
+		panic(e)
+	}
+}
+
+func parseInput() []string {
+	raw_data, err := os.ReadFile("input.txt")
+	check(err)
+	data := string(raw_data[:])
+	lines := strings.Split(strings.TrimSpace(data), "\n")
+	return lines
+}
+
+func part1() {
+	output := 0
+	for _, bank := range parseInput() {
+		max := 0
+		for i, n1 := range bank[:len(bank)-1] {
+			for _, n2 := range bank[i+1:] {
+				new_value, err := strconv.Atoi(string(n1) + string(n2))
+				check(err)
+				if new_value > max {
+					max = new_value
+				}
+			}
+		}
+		output = output + max
+	}
+	fmt.Println(output)
+}
+
+func main() {
+	fmt.Println("Part 1:")
+	part1()
+}