Path Sum 题解

题目来源：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.

解题思路：

递归最简单了。

bool solveRecusive(TreeNode *root, int sum) 
{
    int v = root->val;
    if(root->left == NULL && root->right == NULL)
        return v == sum;
    return (root->left && solveRecusive(root->left, sum-v)) ||
           (root->right && solveRecusive(root->right, sum-v));
}
bool hasPathSum(TreeNode *root, int sum) 
{
    if(root == NULL) return false;//test case rule
    return solveRecusive(root, sum);
}