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struct TreeNode {	int val;	TreeNode *left;	TreeNode *right;	TreeNode(int x) : val(x), left(NULL), right(NULL) {}};class Solution {public:	//recursive to find every path and then sum these path together	void SumRecursive( TreeNode * root, int prev, int& ans ) 	{		if(root == NULL)			return;		prev = prev*10+root->val;		if (root->left == NULL && root->right == NULL)		{//one path is over			ans += prev;			return;		}		SumRecursive(root->left, prev, ans);		SumRecursive(root->right, prev, ans);	}    int sumNumbers(TreeNode *root) {        // Start typing your C/C++ solution below        // DO NOT write int main() function		int ans = 0;		SumRecursive(root, 0, ans);		return ans;    }};

second time

/** * 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 sumNumbersUtil(TreeNode* root, int curSum, int& totalSum)    {        curSum = curSum*10+root->val;        if(root->left == NULL && root->right == NULL)        {            totalSum += curSum;            return ;        }        if(root->left != NULL) sumNumbersUtil(root->left, curSum, totalSum);        if(root->right != NULL) sumNumbersUtil(root->right, curSum, totalSum);    }    int sumNumbers(TreeNode *root) {        // Start typing your C/C++ solution below        // DO NOT write int main() function        if(root == NULL) return 0;        int totalSum = 0;        int curSum = 0;        sumNumbersUtil(root, curSum, totalSum);        return totalSum;    }};

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