112. 路径总和

原题

https://leetcode.cn/problems/path-sum/description/

思路

递归

复杂度

时间：O(n)
空间：O(n)

Python代码

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def hasPathSum(self, root: Optional[TreeNode], targetSum: int) -> bool:
        if not root:
            return False
        if root.left is None and root.right is None:
            return root.val == targetSum
        return self.hasPathSum(root.left, targetSum - root.val) or self.hasPathSum(
            root.right, targetSum - root.val
        )

Go代码

/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */
func hasPathSum(root *TreeNode, targetSum int) bool {
	if root == nil {
		return false
	}
	if root.Left == nil && root.Right == nil {
		return root.Val == targetSum
	}
	return hasPathSum(root.Left, targetSum-root.Val) || hasPathSum(root.Right, targetSum-root.Val)
}