leetcode Next Permutation

经典的排列算法

public class Solution {
    public void nextPermutation(int[] nums) {
        if(nums.length==1)
        {
            return;
        }
        int a=nums.length-2;
        while(a>=0&&nums[a+1]<=nums[a])
        {
            a--;
        }
        if(a==-1)
        {
            reverse(nums,0,nums.length-1);
            return;
        }
        int b=nums.length-1;
        while(nums[b]<=nums[a])
        {
            b--;
        }
        int temp=nums[b];
        nums[b]=nums[a];
        nums[a]=temp;
        reverse(nums,a+1,nums.length-1);
    }

    public void reverse(int []nums,int start,int end)
    {
        for(int i=start,j=end;i<j;i++,j--)
        {
            int temp=nums[i];
            nums[i]=nums[j];
            nums[j]=temp;
        }
    }
}