add sol

leetcode/leetcode75/BinaryTree-DFS/437.PathSumIII/pathSumIII.go

@@ -0,0 +1,60 @@
+package main
+
+import (
+	"fmt"
+)
+
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ *     Val int
+ *     Left *TreeNode
+ *     Right *TreeNode
+ * }
+ */
+
+type TreeNode struct {
+	Val   int
+	Left  *TreeNode
+	Right *TreeNode
+}
+
+func pathSum(root *TreeNode, targetSum int) int {
+	cnt := map[int]int{0: 1}
+	var dfs func(*TreeNode, int) int
+	dfs = func(root *TreeNode, sum int) int {
+		if root == nil {
+			return 0
+		}
+		sum += root.Val
+		result := cnt[sum-targetSum]
+		cnt[sum]++
+		result += dfs(root.Left, sum) + dfs(root.Right, sum)
+		cnt[sum]--
+		return result
+	}
+
+	return dfs(root, 0)
+}
+
+func main() {
+	// Define the trees
+	root := &TreeNode{
+		Val: 10,
+		Left: &TreeNode{
+			Val:  5,
+			Left: &TreeNode{Val: 3},
+			Right: &TreeNode{
+				Val:   2,
+				Right: &TreeNode{Val: 1},
+			},
+		},
+		Right: &TreeNode{
+			Val:   -3,
+			Right: &TreeNode{Val: 11},
+		},
+	}
+	targetSum := 8
+
+	fmt.Println(pathSum(root, targetSum))
+}