LeetCode OJ：Permutations（排列）

Given a collection of numbers, return all possible permutations.

For example,
[1,2,3] have the following permutations:
[1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1].

排列组合的问题，不用考虑是否发生重复的情况，代码如下：

 1 class Solution {
 2 public:
 3     vector<vector<int>> permute(vector<int>& nums) {
 4         memset(mark, 0, sizeof(mark));
 5         memset(cdds, 0, sizeof(cdds));
 6         dfs(0, nums.size(), nums);
 7         return ret;
 8     }
 9
10     void dfs(int dep, int maxDep, vector<int> & nums)
11     {
12         if(dep == maxDep){
13             tmp.clear();
14             for(int i = 0;i < maxDep; ++i)
15                 tmp.push_back(cdds[i]);
16             ret.push_back(tmp);
17         }else{
18             for(int i = 0; i < maxDep; ++i){
19                 if(!mark[i]){
20                     mark[i] = true;
21                     cdds[dep] = nums[i];
22                     dfs(dep + 1, maxDep, nums);
23                     mark[i] = false;
24                 }
25             }
26         }
27     }
29 private:
30     int cdds[100];
31     bool mark[100];
32     vector<int> tmp;
33     vector<vector<int>> ret;
34
35 };