Added the first days

2021/05/second_v2.go

@@ -0,0 +1,58 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+
+	"git.adyxax.org/aoc/2021/05/line"
+)
+
+func abs(a int) int {
+	if a < 0 {
+		return -a
+	}
+	return a
+}
+
+func computeDelta(a, b int) int {
+	if a < b {
+		return 1
+	} else if a > b {
+		return -1
+	}
+	return 0
+}
+
+func main() {
+	matrix := make([][]int, 1000)
+	for i := 0; i < 1000; i++ {
+		matrix[i] = make([]int, 1000)
+	}
+
+	parser := line.NewParser(bufio.NewReader(os.Stdin))
+	for {
+		l, err := parser.Parse()
+		if err != nil {
+			break
+		}
+		length := abs(l.X2 - l.X1)
+		if length == 0 {
+			length = abs(l.Y2 - l.Y1)
+		}
+		dx := computeDelta(l.X1, l.X2)
+		dy := computeDelta(l.Y1, l.Y2)
+		for i := 0; i <= length; i++ {
+			matrix[l.X1+i*dx][l.Y1+i*dy]++
+		}
+	}
+	score := 0
+	for i := 0; i < 1000; i++ {
+		for j := 0; j < 1000; j++ {
+			if matrix[i][j] >= 2 {
+				score++
+			}
+		}
+	}
+	fmt.Println(score)
+}