## Saturday, March 23, 2013

### [LeetCode] Path Sum, Solution

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.
» Solve this problem

[Thoughts]

[Code]
``````1:       bool hasPathSum(TreeNode *root, int sum) {
2:            return hasPathSum(root, 0, sum);
3:       }
4:       bool hasPathSum(TreeNode *root, int sum, int target) {
5:            if(root == NULL) return false;
6:            sum += root->val;
7:            if(root->left == NULL && root->right == NULL) //leaf
8:            {
9:                 if(sum == target)
10:                      return true;
11:                 else
12:                      return false;
13:            }
14:            return hasPathSum(root->left, sum, target)
15:                   || hasPathSum(root->right, sum, target);
16:       }
``````