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[Leetcode] 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.

 

Solution:

 1 /** 2  * Definition for binary tree 3  * public class TreeNode { 4  *     int val; 5  *     TreeNode left; 6  *     TreeNode right; 7  *     TreeNode(int x) { val = x; } 8  * } 9  */10 public class Solution {11     public boolean hasPathSum(TreeNode root, int sum) {12         return dfs(root,sum,0);13     }14 15     private boolean dfs(TreeNode root, int sum, int curSum) {16         // TODO Auto-generated method stub17         if(root==null)18             return false;19         if(root.left==null&&root.right==null)20             return (curSum+root.val)==sum;21         return dfs(root.left,sum,curSum+root.val)||dfs(root.right, sum, curSum+root.val);22     }23 }

 

[Leetcode] Path Sum