【leetcode】Path Sum II

Question：

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]]

Anwser 1：     

/** * 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 calPath(TreeNode *root, int sum, vector<int> tmp, vector< vector<int> > &ret){        if(root == NULL){            return;        }                tmp.push_back(root->val);        if(sum == root->val && root->left == NULL && root->right == NULL){            ret.push_back(tmp);        }                calPath(root->left, sum - root->val, tmp, ret);        calPath(root->right, sum - root->val, tmp, ret);                tmp.pop_back();    }    vector<vector<int> > pathSum(TreeNode *root, int sum) {        // Start typing your C/C++ solution below        // DO NOT write int main() function        vector< vector<int> > ret;                if(root == NULL) {            return ret;        }                vector<int> tmp;        calPath(root, sum, tmp, ret);        return ret;    }};

Anwser 2：    

/** * 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 calPath(TreeNode *root, int sum, vector<int> tmp, vector< vector<int> > &ret){        if(root == NULL){            return;        }                tmp.push_back(root->val);        if(sum == root->val && root->left == NULL && root->right == NULL){            ret.push_back(tmp);            tmp.pop_back();     // pop tmp vector            return;        }                calPath(root->left, sum - root->val, tmp, ret);        calPath(root->right, sum - root->val, tmp, ret);                tmp.pop_back();    }    vector<vector<int> > pathSum(TreeNode *root, int sum) {        // Start typing your C/C++ solution below        // DO NOT write int main() function        vector< vector<int> > ret;                if(root == NULL) {            return ret;        }                vector<int> tmp;        calPath(root, sum, tmp, ret);        return ret;    }};