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   1return[   [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 {public:    vector<vector<int>> pathSum(TreeNode* root, int sum) {        vector<vector<int>> res;        if(!root) return res;        vector<int> tmp;        dfs(root,sum,res,tmp);        return res;    }    void dfs(TreeNode* root,int sum,vector<vector<int>> &res,vector<int> &tmp){        if(!root) return ;        sum -=root->val;        tmp.push_back(root->val);        if(!root->left && !root->right && sum==0) res.push_back(tmp);        dfs(root->left,sum,res,tmp);        if(root->left) tmp.pop_back();        dfs(root->right,sum,res,tmp);        if(root->right) tmp.pop_back();    }};