import java.util.ArrayList;

public class Solution {
    /**
     * @param nums: A list of integers
     * @return: A list of integers that's previous permuation
     */
    public void swapItem(ArrayList<Integer> nums, int i, int j) {
        Integer tmp = nums.get(i);
        nums.set(i, nums.get(j));
        nums.set(j, tmp);
    }
    public void swapList(ArrayList<Integer> nums, int i, int j) {
        while ( i < j) {
            swapItem(nums, i, j);
            i ++; j --;
        }
    }
    public ArrayList<Integer> previousPermuation(ArrayList<Integer> nums) {
        int len = nums.size();
        if ( len <= 1)
            return nums;
        int i = len - 1;
        while ( i > 0 && nums.get(i) >= nums.get(i-1) )
            i --;
        swapList(nums, i, len - 1);
        if ( i != 0) {
            int j = i;
            while ( nums.get(j) >= nums.get(i-1) ) j++;
            swapItem(nums, j, i-1);
        }

        return nums;
    }
}