C++ :

#include<cstdio>
#include<cstdlib>
#include<iostream>
using namespace std;
int n,r;
bool a[25]={0};
int b[25];
int print()
{
	for(int i=1;i<=r-1;++i)
	{
		printf("%d ",b[i]);
	}
	printf("%d\n",b[r]);
}
int search(int i)
{
	for(int j=1;j<=n;++j)
	{
		if(a[j]==0&&j>b[i-1])
		{
			b[i]=j;
			a[j]=1;
			if(i==r)
			{
				print();
			}
			else
			{
				search(i+1);
			}
			a[j]=0;
		}
		
	}
}
int main()
{
	cin>>n>>r;
	search(1);
	return 0;
}

Pascal :

var i,j,k,l,m,n:longint;
 a:array[1..100] of byte;
 procedure  try(num,l:longint);
   var i,j:longint;
    begin
     if num=k+1 then begin for i:=1 to k do begin write(a[i]);if i<>k then write(' ');end;writeln;exit;end;
     for i:=l+1 to m-k+num do
       begin
        a[num]:=i;try(num+1,i);
       end;
    end;
  begin
   read(m,k);
    try(1,0);
  end.

Java :

import java.util.Scanner;

public class Main {
	static int M,N;
	static int [] arr;
	public static void main(String[] args) {
		Scanner cin = new Scanner(System.in);
		M = cin.nextInt();
		N = cin.nextInt();
		arr = new int[N+1];
		combin(M,N);
	}
	public static void combin(int m,int n) {
		if(n == 0) {
			for(int i = 1; i <= N; i ++) {
				System.out.print(arr[i]);
				if(i == N)
					System.out.println();
				else
					System.out.print(" ");
			}
		}else if(m < n){
			return ;
		}else {
			combin(m-1,n);
			arr[n] = m;
			combin(m-1,n-1);
			}
		}
}