From 1f8652c176ebf1baf02f1b5949db3b5ca49f7bdc Mon Sep 17 00:00:00 2001
From: Kharec <sandro@cazzaniga.fr>
Date: Mon, 24 Nov 2025 14:01:57 +0100
Subject: [PATCH] feat: add main code

---
 2020/day03/main.go | 62 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100644 2020/day03/main.go

diff --git a/2020/day03/main.go b/2020/day03/main.go
new file mode 100644
index 0000000..b1b9190
--- /dev/null
+++ b/2020/day03/main.go
@@ -0,0 +1,62 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"strings"
+)
+
+func parseInput(file string) []string {
+	content, err := os.ReadFile(file)
+	if err != nil {
+		log.Fatalf("Faild to read input file: %v", err)
+	}
+	lines := strings.Split(string(content), "\n")
+	var data []string
+	for _, line := range lines {
+		data = append(data, line)
+	}
+	return data
+}
+
+func PartOne(input []string) int {
+	trees := 0
+	column := 0
+	for row := range input {
+		if len(input[row]) == 0 {
+			continue
+		}
+		if input[row][column%len(input[row])] == '#' {
+			trees++
+		}
+		column += 3
+	}
+	return trees
+}
+
+func PartTwo(input []string) int {
+	result := 1
+	slopes := [][]int{{1, 1}, {3, 1}, {5, 1}, {7, 1}, {1, 2}}
+	for _, slope := range slopes {
+		trees := 0
+		column := 0
+		for row := 0; row < len(input); row += slope[1] {
+			if len(input[row]) == 0 {
+				continue
+			}
+			if input[row][column%len(input[row])] == '#' {
+				trees++
+			}
+			column += slope[0]
+		}
+		result *= trees
+	}
+	return result
+}
+
+func main() {
+	data := parseInput("input.txt")
+	fmt.Println("Part 1:", PartOne(data))
+	fmt.Println("Part 2:", PartTwo(data))
+}