part 2

Author: Robb Kidd

2022/go/day04/main.go

@@ -37,6 +37,39 @@ func fullyCovers(pair Pair) bool {
 	return false
 }
 
+func p2(lines []string) int {
+	var overlapped int
+	for _, line := range lines {
+		pair := lineToPair(line)
+
+		if overlaps(pair) {
+			overlapped++
+			continue
+		}
+	}
+	return overlapped
+}
+
+func overlaps(pair Pair) bool {
+	if fullyCovers(pair) {
+		return true
+	}
+
+	if pair.left.start >= pair.right.start && pair.left.start <= pair.right.stop {
+		return true
+	}
+	if pair.right.start >= pair.left.start && pair.right.stop <= pair.left.stop {
+		return true
+	}
+	if pair.left.stop >= pair.right.start && pair.left.stop <= pair.right.stop {
+		return true
+	}
+	if pair.right.stop >= pair.left.start && pair.right.stop <= pair.left.stop {
+		return true
+	}
+	return false
+}
+
 func lineToPair(line string) Pair {
 	p := strings.Split(line, ",")
 	left := strings.Split(p[0], "-")
@@ -59,10 +92,6 @@ func lineToPair(line string) Pair {
 	}
 }
 
-func p2(input []string) int {
-	return 0
-}
-
 type Pair struct {
 	left  Assignment
 	right Assignment

2022/go/day04/main_test.go

@@ -12,17 +12,18 @@ func TestExamplePart1(t *testing.T) {
 		p1(parseInput(example)))
 }
 
-// func TestExamplePart2(t *testing.T) {
-// 	assert.Equal(t,
-// 		'heyo',
-// 		p2(parseInput(example)))
-// }
+func TestExamplePart2(t *testing.T) {
+	assert.Equal(t,
+		4,
+		p2(parseInput(example)))
+}
 
 const (
 	example = `2-4,6-8
 2-3,4-5
 5-7,7-9
 2-8,3-7
 6-6,4-6
-2-6,4-8`
+2-6,4-8
+`
 )