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LeetCode:Sum Root to Leaf Numbers

时间:2014-06-15 14:51:02      阅读:167      评论:0      收藏:0      [点我收藏+]

标签:leetcode

     Given a binary tree containing digits from 0-9 only, each root-to-leaf path


could represent a number.


An example is the root-to-leaf path 1->2->3 which represents the number 123.


Find the total sum of all root-to-leaf numbers.


For example,

    1
   /   2   3
 

The root-to-leaf path 1->2 represents the number 12.


The root-to-leaf path 1->3 represents the number 13.


Return the sum = 12 + 13 = 25.


解题思路:

    遍历二叉树,即可得知根到叶子节点的数,由于数据比较弱,路径上的数字用


int就能存下,如果树的深度大于10,int就会溢出,所以较好的做法是用字符串,


然后模拟加法运算即可.


解题代码:

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    void dfs(TreeNode *rt,int path,int &sum)
    {
        if (!rt) return ;
        path = path * 10 + rt->val ;
        if (rt->left == rt->right && !rt->left)
            sum +=path;
        dfs(rt->left,path,sum);
        dfs(rt->right,path,sum);
    }
    int sumNumbers(TreeNode *root) 
    {
        int ans = 0 ;
        dfs(root,0,ans);
        return ans ;
    }
};


LeetCode:Sum Root to Leaf Numbers,布布扣,bubuko.com

LeetCode:Sum Root to Leaf Numbers

标签:leetcode

原文地址:http://blog.csdn.net/dream_you_to_life/article/details/30759245

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