leetcode31 下一个排列

class Solution {
public:
    // 8 4 7 6 5 3 1
    void nextPermutation(vector<int>& nums) {
        int len = nums.size();
        int i,j;
        for(i=len-2;i>=0;--i)   //找4
        {
            if(nums[i]<nums[i+1])
                break;
        }
        if(i<0) //都按升序排列
            reverse(nums.begin(),nums.end());
        else
        {
            for(j=len-1;j>i;--j)    //找5
            {
                if(nums[j]>nums[i])
                    break;
            }
            swap(nums[i],nums[j]);
            reverse(nums.begin()+i+1,nums.end()); //反序76431
                
        }
        
    }
};

参考
https://leetcode.com/problems/next-permutation/discuss/13867/C%2B%2B-from-Wikipedia