LeetCode 112 Path Sum

LeetCode 112

Path Sum

• Problem Description：
  给出一棵二叉树，计算二叉树中从根节点到各个叶节点的节点和，如果其中存在等于题目给出的定值sum，则返回true，否则返回false.

  具体的题目信息：
  https://leetcode.com/problems/path-sum/description/

• Example:
  
• Solution:

/**
 * 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->left == NULL && root->right == NULL && sum-root->val == 0) return true;
        return hasPathSum(root->left, sum-root->val)||hasPathSum(root->right, sum-root->val);
    }
};