leetcode_c++:树: Path Sum（112）

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.

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class Solution {public:    bool hasPathSum(TreeNode *root, int sum) {        if (root == NULL)            return false;        if (!root->left && !root->right)            return sum == root->val;        return hasPathSum(root->left, sum - root->val) ||            hasPathSum(root->right, sum - root->val);    }};