package com.app.main.LeetCode.tree;
import com.app.main.LeetCode.base.TreeNode;
/**
* 112
*
* easy
*
* https://leetcode.com/problems/path-sum/
*
* 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.
*
* Created with IDEA
* author:Dingsheng Huang
* Date:2019/11/1
* Time:上午10:48
*/
public class PathSum {
public boolean hasPathSum(TreeNode root, int sum) {
return process(root, sum, 0);
}
private boolean process (TreeNode root, int sum, int curr) {
if (root == null) {
return false;
}
curr += root.val;
// 当前节点为叶子节点，且累计值等于目标值
if (root.left == null && root.right == null && curr == sum) {
return true;
}
return process(root.left, sum, curr) ||process(root.right, sum, curr);
}
}
