LeetCode Sum Root to Leaf Numbers

链接: https://oj.leetcode.com/problems/sum-root-to-leaf-numbers/

dfs..sum保存中间结果.每计算完一条路径,就更新ans

/**
 * 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 ans;
		int sumNumbers(TreeNode *root)
		{
			ans=0;
			if(root==NULL)
				return 0;
			dfs(root,root->val);
			return ans;
		}
		void dfs(TreeNode *root,int sum)
		{
			if(root->left==NULL&&root->right==NULL)
			{
				ans+=sum;
				return ;
			}
			if(root->left)	
				dfs(root->left,sum*10+root->left->val);
			if(root->right)
				dfs(root->right,sum*10+root->right->val);
		}
};