Arrays Arrange 3

public class Solution {
    public int[] nextPermutation(int[] arr) {
        if(arr.length <= 1){
            return arr;
        }
        int i = arr.length-1;
        while(i>0 && arr[i-1] >= arr[i]){
            i--;
        }
        if(i == 0){
            reverse(arr,i);
            return arr;
        }
        int j = i+1;
        while(j<arr.length && arr[j] > arr[i-1]){
            j++;
        }
        swap(arr,i-1,j-1);
        reverse(arr,i);
        return arr;
    }
    public void reverse(int[] arr, int i){
        int j = arr.length-1;
        while(i<j){
            swap(arr,i,j);
            i++;
            j--;
        }
    }
    
    public void swap(int arr[], int i, int j){
        int temp = arr[i];
        arr[i] = arr[j];
        arr[j] = temp;
    }
}