Path Sum in Binary Tree

Problem Statement

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.

Solution

[sourcecode language="cpp"]
class Solution
{
public:
bool hasPathSum(TreeNode *root, int sum)
{
bool l=false,r=false;
if( root == NULL )
return false;

if(root->left == NULL && root->right == NULL)
{
if( (sum - root->val) == 0 )
return true;
return false;
}

if( root->left != NULL )
l = hasPathSum(root->left,sum-root->val);

if( root->right != NULL )
r = hasPathSum(root->right,sum - root->val);

return l|r;
}

};

[/sourcecode]