Merge pull request #416 from vaskoz/day201

Day201

README.md

@@ -211,3 +211,4 @@ problems from
 * [Day 198](https://github.com/vaskoz/dailycodingproblem-go/issues/408)
 * [Day 199](https://github.com/vaskoz/dailycodingproblem-go/issues/409)
 * [Day 200](https://github.com/vaskoz/dailycodingproblem-go/issues/411)
+* [Day 201](https://github.com/vaskoz/dailycodingproblem-go/issues/415)

day201/problem.go

@@ -0,0 +1,25 @@
+package day201
+
+// MaxWeightPathTriangle returns the weight of the maximum weight path
+// as defined by the problem.
+// Runs in O(N) time.
+// Assumes a correct triangle as input.
+func MaxWeightPathTriangle(tri [][]int) int {
+	return maxWeightPathTriangleHelper(tri, 0, 0)
+}
+
+func maxWeightPathTriangleHelper(tri [][]int, row, col int) int {
+	if row == len(tri)-1 {
+		return tri[row][col]
+	}
+	left := maxWeightPathTriangleHelper(tri, row+1, col)
+	right := maxWeightPathTriangleHelper(tri, row+1, col+1)
+	return tri[row][col] + max(left, right)
+}
+
+func max(a, b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}

day201/problem_test.go

@@ -0,0 +1,27 @@
+package day201
+
+import "testing"
+
+var testcases = []struct {
+	triangle  [][]int
+	maxWeight int
+}{
+	{[][]int{{1}, {2, 3}, {1, 5, 1}}, 9},
+}
+
+func TestMaxWeightPathTriangle(t *testing.T) {
+	t.Parallel()
+	for _, tc := range testcases {
+		if result := MaxWeightPathTriangle(tc.triangle); result != tc.maxWeight {
+			t.Errorf("Expected %v, got %v", tc.maxWeight, result)
+		}
+	}
+}
+
+func BenchmarkMaxWeightPathTriangle(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for _, tc := range testcases {
+			MaxWeightPathTriangle(tc.triangle)
+		}
+	}
+}