C++ 解法, 执行用时: 0ms, 内存消耗: 8552KB, 提交时间: 2015-04-03

/**
 * 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 sumNumbers(TreeNode *root) {
        int result=0;
        sumNumbers2(root, result);
         
        return result;
    }
     
    void sumNumbers2(TreeNode *root, int &result)
    {
        if(root == NULL)
        {
            return;
        }
         
        path.push_back(root->val);
         
        if(root->left==NULL && root->right==NULL)
        {
            int sum=0;
            for(vector<int>::iterator it=path.begin();it!=path.end();it++)
            {
                sum=sum*10+*it;
            }
            result+=sum;
        }
         
        if(root->left!=NULL)
        {
            sumNumbers2(root->left, result);
        }
        if(root->right!=NULL)
        {
            sumNumbers2(root->right, result);
        }
        path.pop_back();
    }
private:
    vector<int> path;
};

C++ 解法, 执行用时: 0ms, 内存消耗: 8552KB, 提交时间: 2015-04-03

/**
 * 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 sumNumbers(TreeNode *root) {
        if (root == NULL)
            return 0;
        if ((root->left == NULL) && (root->right == NULL))
            return root->val;
        stack <TreeNode *> pstack;
        stack <int> vstack;
        TreeNode *ptr = root;
        int sum = 0, temp = 0;
        int flag;
        while(ptr){
            flag = 0;
            temp = temp * 10 + ptr->val;
            if(ptr->right != NULL){
                pstack.push(ptr->right);
                vstack.push(temp);
                flag = 1;
            }
            if(ptr->left != NULL){
                ptr = ptr->left;
            }
            else{
                if(!flag){
                    sum += temp;
                }
                if(!pstack.empty()){
                    ptr = pstack.top();
                    pstack.pop();
                    temp = vstack.top();
                    vstack.pop();
                }
                else
                    break;
            }
        }
        //delete ptr;
        return sum;
    }
};

C++ 解法, 执行用时: 0ms, 内存消耗: 8552KB, 提交时间: 2015-03-28

/**
 * 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 sumNumbers(TreeNode *root) {
		if (root == NULL)
			return 0;
		
		return calc(root, 0);
	}

	int calc(TreeNode* root, int curVal) {
		//if is leaf
		if (root->left == NULL && root->right == NULL)
			return curVal * 10 + root->val;
		
		int leftVal = 0, rightVal = 0;
		if (root->left != NULL)
			leftVal = calc(root->left, curVal * 10 + root->val);
		if (root->right != NULL)
			rightVal = calc(root->right, curVal * 10 + root->val);
		return leftVal + rightVal;
	}
};

C++ 解法, 执行用时: 0ms, 内存消耗: 8552KB, 提交时间: 2015-03-27

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

C++ 解法, 执行用时: 0ms, 内存消耗: 8552KB, 提交时间: 2015-03-11

class Solution {
public:
    int sumNumbers(TreeNode *root) {
        return dfs( root, 0);
    }
    int dfs(TreeNode *root, int sum) {
        if ( root == nullptr ) return 0;
        if ( root->left == nullptr && root->right == nullptr )
               return sum * 10 + root->val;
        return dfs(root->left, sum * 10 + root->val)
              + dfs(root->right, sum * 10 + root->val);
    }
};