Hãy viết chương trình liệt kê tất cả các hoán vị của 1, 2, .., n.

package bai11;

import java.util.Scanner;

public class Main {

  public static int nhap(){

                Scanner input= new Scanner(System.in);

                boolean check= false;

                int n=0;

                while(!check){

                       System.out.print(" ");

                       try{

                             n= input.nextInt();

                             check= true;

                       }catch(Exception e){

                              System.out.println("Ban phai nhap so! hay nhap lai...");

                              input.nextLine();

                       }

                }

                return (n);

      }

  public static void main(String[] args) {

    System.out.print("Nhap n");

            int n= nhap();

            int[] array= new int[n+2];

            int i,j,k=n-1,temp,check=1;

            for(i=0 ; i<n ; i++){

                      array[i]= i+1;

            }

            System.out.println("Cac hoan vi ke la: ");

            try{

                    i= n-2;

                    while(check>0){

                          //In ra hoan vi System.out.println(" ");

                          for(j=0 ; j<n ; j++){

                                    System.out.print(" "+array[j]);

                          }

                          for(i= n-2 ; i>=0 ; i--){

                                       check= 1;

                          if(array[i] < array[i+1]){

                                  if(i==n-2){

                                        temp= array[i];

                                        array[i]= array[n-1];

                                        array[n-1]= temp;

                                        break;

                                  }

                                  else{

                                         //Tim so a[k] nho nhat ma >a[i] trong cac so ben phai a[i]

                                         k= i+1;

                                             for(j=i+1 ; j<n ; j++){

                                                    if(array[i+1]>array[j] && array[j]>array[i]) k=j;

                                             }

                                             //Doi cho a[k] va a[i]

                                             temp= array[i];

                                             array[i]= array[k];

                                             array[k]= temp;

                                         //Sap xep lai tu a[i+1] toi a[n]

                                         for(j=i+1 ; j<n ; j++){

                                               for(int m= i+1 ; m<n ; m++){

                                                       if(array[j]<array[m]){

                                                               temp= array[j];

                                                               array[j]= array[m];

                                                               array[m]= temp;

                                                       }

                                               }

                                         }

                                         break;

                                 }

                   }

                   else {

                           check=0;

                   // break;

                   }

                   }

                   //if(i==0)check=0;

              }

          }catch(Exception e){}

  }

}