LeetCode | Path-Sum
题目描述
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 andsum = 22,
5 / \ 4 8 / / \ 11 13 4 / \ \ 7 2 1
return true, as there exist a root-to-leaf path5->4->11->2which sum is 22.
题目意思: 是判断是否有从根节点到叶节点的路径和等于给定的sum值。采用递归实现,具体代码如下!
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 if (root == null) 13 return false; 14 if (root.left == null && root.right == null && sum == root.val) { 15 return true; 16 } 17 return (hasPathSum(root.left, sum-root.val) || hasPathSum(root.right, sum-root.val)); 18 } 19 }