문제
Given the root of a binary tree and an integer targetSum, return true if the tree has a root-to-leaf path such that adding up all the values along the path equals targetSum.
A leaf is a node with no children.
https://leetcode.com/problems/path-sum/description/
Example 1:
Input: root = [5,4,8,11,null,13,4,7,2,null,null,null,1], targetSum = 22
Output: true
Explanation: The root-to-leaf path with the target sum is shown.
Example 2:
Input: root = [1,2,3], targetSum = 5
Output: false
Explanation: There two root-to-leaf paths in the tree:
(1 --> 2): The sum is 3.
(1 --> 3): The sum is 4.
There is no root-to-leaf path with sum = 5.
Example 3:
Input: root = [], targetSum = 0
Output: false
Explanation: Since the tree is empty, there are no root-to-leaf paths.
풀이
class Solution {
public boolean hasPathSum(TreeNode root, int targetSum) {
if(root == null) return false;
if(root.left == null && root.right == null && targetSum - root.val == 0) return true;
return hasPathSum(root.left, targetSum - root.val)
|| hasPathSum(root.right, targetSum - root.val);
}
}