LeetCode题解——Path Sum

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.

it's easy to use recursion to solve the problem

/**
* 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) return false;
if(!root->left && !root->right) return sum==root->val;
bool flage = false;
if(root->left) flage = hasPathSum(root->left,sum-root->val);
if(flage) return true;
else{
if(root->right) return hasPathSum(root->right,sum-root->val);
else return false;
}
}
};