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Path Sum

时间:2015-10-11 22:49:45      阅读:184      评论:0      收藏:0      [点我收藏+]

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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.

 

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */
bool hasPathSum(struct TreeNode* root, int sum) {
    bool left, right;
    if(root == NULL)
        return false;
    else if(root->val == sum && root->left == NULL && root->right == NULL)
        return true;
    else
        {
            left = hasPathSum(root->left, sum - root->val);
            right = hasPathSum(root->right, sum - root->val);
            return (left || right);
        }
}
  • 关于递归,好像摸到了一些门道
  • 先写出最简单的时候的情况,然后对于可以归类的进行递归,要注意每次的递归的返回值

Path Sum

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原文地址:http://www.cnblogs.com/dylqt/p/4870143.html

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