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  • leetcode 112 Path Sum ----- java

    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.

    给定一棵树和一个数,判断这个数是不是从根节点到叶子节点的和。

    递归实现很简单。

    /**
     * Definition for a binary tree node.
     * public class TreeNode {
     *     int val;
     *     TreeNode left;
     *     TreeNode right;
     *     TreeNode(int x) { val = x; }
     * }
     */
    public class Solution {
        public boolean hasPathSum(TreeNode root, int sum) {
            
            if( root == null)
                return false;
            if( root.left == null && root.right == null)
                return sum==root.val;
            
            return hasPathSum(root.left,sum-root.val)||hasPathSum(root.right,sum-root.val);
            
        }
    }
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  • 原文地址:https://www.cnblogs.com/xiaoba1203/p/6011380.html
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