# leetcode 46. Permutations (生成全排列，无重复元素)

Posted by 111qqz on Thursday, April 13, 2017

## TOC

Given a collection of distinct numbers, return all possible permutations.

``````/* ***********************************************
Author :111qqz
Created Time :2017年04月13日 星期四 14时49分34秒
File Name :46.cpp
************************************************ */
class Solution {

public:

void solve(vector<int> &nums)
{
int n = nums.size();
if (n==0) return;
int k = -1;
for ( int i = n-2 ; i >= 0 ; i--)
{
if (nums[i]<nums[i+1])
{
k = i ;
break;
}
}
if (k==-1)
{
reverse(nums.begin(),nums.end());
return;
}
int l = -1;
for ( int i = n-1 ; i > k ; i-- )
{
if (nums[k]<nums[i])
{
l = i ;
break;
}
}
swap(nums[l],nums[k]);
reverse(nums.begin()+k+1,nums.end());
}
vector<vector<int>> permute(vector<int>& nums) {
vector<vector<int> >res;
int n = nums.size();
int total = 1;
for ( int i = 2 ; i <= n ; i++) total*=i;
for ( int i = 1 ; i <= total; i++)
{
res.push_back(nums);
solve(nums);
}

return res;
}

};
``````

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