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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 stub 17 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 }
标签：style blog io color ar sp for div on
原文地址：http://www.cnblogs.com/Phoebe815/p/4100932.html
