LeetCode OJ--Next Permutation *

1,2,3

1,3,2

3,2,1

1,2,3

1,1,5

1,5,1

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

class Solution{
public:
void nextPermutation(vector<int> &num) {
if(num.size() == 0)
return;

const vector<int>::reverse_iterator rfirst= num.rbegin();
const vector<int>::reverse_iterator rend = num.rend();

auto pivot = next(rfirst);
while(pivot != rend && *pivot >= *prev(pivot))
{
++pivot;
}

if(pivot == rend)
{
reverse(rfirst,rend);
return;
}
//find the first num great than pivot
auto change = rfirst;
while(*change<=*pivot)
++change;

swap(*change,*pivot);
reverse(rfirst,pivot);
return;
}
};

int main()
{
vector<int> num;
num.push_back(1);
num.push_back(1);
num.push_back(5);

Solution myS;
myS.nextPermutation(num);
return 0;
}