Path Sum

目录

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.

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/**
* Definition for binary tree
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
//一次提交就过、、
public class Solution {
public boolean hasPathSum(TreeNode root, int sum) {
if(root==null){
return false;
}
sum=sum-root.val;
if(root.left==null&&root.right==null&&sum==0){
return true;
}
return (hasPathSum(root.left,sum)||hasPathSum(root.right,sum));
}
}