113. Path Sum II

Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum.

For example:
Given the below binary tree and sum = 22,

              5             / \            4   8           /   / \          11  13  4         /  \    / \        7    2  5   1

return

[   [5,4,11,2],   [5,8,4,5]]

/** * Definition for a binary tree node. * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {private:    vector<vector<int>> result;public:        void pathPlus(TreeNode * root, int sum, vector<int> &vec)    {        if(root->left==NULL && root->right==NULL)        {            vector<int>::iterator iter = vec.begin();            int totalsum = 0;            for( ; iter != vec.end() ; iter++)            {                totalsum += *iter;            }                        if(totalsum == (sum-root->val))            {                vec.push_back(root->val);                result.push_back(vec);                vec.pop_back();            }               return;        }                cout<<root->val<<endl;                vec.push_back(root->val);        if(root->left)            pathPlus(root->left, sum, vec);        if(root->right)                pathPlus(root->right, sum, vec);        vec.pop_back();    }        void pathMinus(TreeNode * root, int sum, vector<int> &vec)    {        if(root->left==NULL && root->right==NULL && sum == root->val)        {                                       vec.push_back(root->val);                result.push_back(vec);                vec.pop_back();                return;        }                cout<<root->val<<endl;                vec.push_back(root->val);        if(root->left)            pathMinus(root->left, sum-root->val, vec);        if(root->right)                pathMinus(root->right, sum-root->val, vec);        vec.pop_back();    }        vector<vector<int>> pathSum(TreeNode* root, int sum) {                if (root == NULL)            return vector<vector<int>>();                vector<int> vec;        pathPlus(root, sum, vec);                return result;    }};