LeetCode *** 46. Permutations

题目：

Given a collection of distinct 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]

.

分析：

dfs搜索即可。

代码：

class Solution {
public:
vector<vector<int>> res;

vector<vector<int>> permute(vector<int>& nums) {
vector<int> tmp;
bool *mark=new bool[nums.size()];
for(int i=0;i<nums.size();++i)mark[i]=false;
dfs(tmp,nums,mark);
return res;
}

void dfs(vector<int>& tmp,vector<int>& nums,bool*& mark){
if(nums.size()==tmp.size()){
res.push_back(tmp);
return;
}

for(int i=0;i<nums.size();++i){
if(!mark[i]){
mark[i]=true;
tmp.push_back(nums[i]);
dfs(tmp,nums,mark);
tmp.erase(tmp.end()-1);
mark[i]=false;
}
}
}
};