112路径总和.cpp

class Solution {
public:
    bool hasPathSum(TreeNode* root, int sum) {
        if (root == NULL) return false;
        if (root->left == NULL && root->right == NULL)  return (sum - root->val) == 0;
        return hasPathSum(root->left, sum - root->val) || hasPathSum(root->right, sum - root->val);
    }
};