【LeetCode】112. Path Sum

时间:2023-12-25 17:43:49

题目:

Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.

For example:
Given the below binary tree and sum = 22,

              5
/ \
4 8
/ / \
11 13 4
/ \ \
7 2 1

return true, as there exist a root-to-leaf path 5->4->11->2 which sum is 22.

提示:

这道题可以用DFS。

代码:

DFS:

/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
bool hasPathSum(TreeNode* root, int sum) {
if (root == NULL) return false;
if (root->val == sum && !root->left && !root->right) return true;
else return hasPathSum(root->left, sum - root->val) || hasPathSum(root->right, sum - root->val);
}
};