437 wrong answer

Author: aQua

Algorithms/0437.path-sum-iii/path-sum-iii.go

@@ -8,18 +8,36 @@ type TreeNode = kit.TreeNode
 
 func pathSum(root *TreeNode, sum int) int {
 	res := 0
-	if root == nil {
-		return res
-	}
+	path := []int{}
+
+	var dfs func(*TreeNode, int, int)
+	dfs = func(node *TreeNode, level, sum int) {
+		if node == nil {
+			return
+		}
+
+		// 根据 level 来更新 path
+		if level >= len(path) {
+			path = append(path, node.Val)
+		} else {
+			path[level] = node.Val
+		}
+		sum -= node.Val
 
-	newSum := sum - root.Val
-	if newSum == 0 {
-		res++
-		return 1 + pathSum(root.Left, sum) + pathSum(root.Right, sum)
+		// 到达 leaf
+		// 并且，此条路径符合要求
+		if node.Left == nil && node.Right == nil && sum == 0 {
+			temp := make([]int, level+1)
+			// copy 不会复制 path[len(temp):]，如果 len(path) > len(temp) 的话
+			copy(temp, path)
+			res = append(res, temp)
+		}
+
+		dfs(node.Left, level+1, sum)
+		dfs(node.Right, level+1, sum)
 	}
 
-	return pathSum(root.Left, sum) +
-		pathSum(root.Right, sum) +
-		pathSum(root.Left, newSum) +
-		pathSum(root.Right, newSum)
+	dfs(root, 0, sum)
+
+	return res
 }

Algorithms/0437.path-sum-iii/path-sum-iii_test.go

@@ -20,10 +20,10 @@ func Test_Problem0437(t *testing.T) {
 	}{
 
 		{
-			[]int{8, 5, 3, 5, -2, 2, 1, -3, 11, 0},
-			[]int{5, 3, -2, 5, 2, 1, 8, -3, 11, 0},
+			[]int{8, 5, 3, 5, -2, 2, 1, -3, 11, 0, 8},
+			[]int{5, 3, -2, 5, 2, 1, 8, -3, 11, 0, 8},
+			8,
 			8,
-			6,
 		},
 
 		// 可以多个 testcase