[leetcode]112. Path Sum路径和(是否有路径)

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.

Note: A leaf is a node with no children.

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.

 

题意：

给定二叉树和一个值，判断从根到叶是否存在一条路径，其路径和等于该值。

 

思路：

dfs

 

代码：

1 class Solution { 2 public boolean hasPathSum(TreeNode root, int sum) { 3 if(root == null) return false; 4 5 if(root.left== null && root.right== null) 6 return root.val == sum; 7 8 if(hasPathSum(root.left, sum - root.val)) 9 return true; 10 if(hasPathSum(root.right, sum - root.val)) 11 return true; 12 13 return false; 14 } 15 }

 

转载于:https://www.cnblogs.com/liuliu5151/p/9171258.html