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.

bool hasPathSum(TreeNode *root, int sum) {if(root == NULL)    return false;if(root->right == NULL && root->left == NULL && root->val == sum)    return true;else    return (hasPathSum(root->left, sum - root->val) || hasPathSum(root->right, sum - root->val));}