LeetCode - Sum Root to Leaf Numbers

最新推荐文章于 2019-05-19 19:00:07 发布

原创最新推荐文章于 2019-05-19 19:00:07 发布 · 378 阅读

0 ·

CC 4.0 BY-SA版权

LeetCode 专栏收录该内容

121 篇文章

订阅专栏

本文介绍了一种算法，用于计算二叉树中所有从根节点到叶子节点的路径所代表数字的总和。通过递归遍历的方式，将每个路径上的数字累加并返回最终的总和。

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.

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

};