# LeetCode112. Path Sum（二叉树 / 搜索）

## LeetCode112. Path Sum（二叉树 / 搜索）

• Easy
• Accepted：290,680
• Submissions：782,733

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.

Note: A leaf is a node with no children.

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.

### 链接

https://leetcode.com/problems/path-sum

### 代码

• Runtime: 16 ms, faster than 99.96% of C++ online submissions for Path Sum.
• Memory Usage: 20 MB, less than 14.90% of C++ online submissions for Path Sum.
class Solution {
public:
bool hasPathSum(TreeNode* root, int sum) {
if (root == NULL)
return false;
if (root->val == sum && root->left == NULL && root->right == NULL) // 当前结点是否符合条件
return true;
return hasPathSum(root->left, sum - root->val) || hasPathSum(root->right, sum - root->val); // 递归判断左右子树
}
};

The end.
2019年3月15日 星期五