package algorithm;

import java.util.*;

public class PermMain {

static int N = 4, R = 3, C;

static int[] a = { 1, 2, 3, 4 }, b = new int[R];

static boolean[] v = new boolean[N];

static void perm(int cnt) {

if (cnt == R) {

System.out.println(Arrays.toString(b));

C++;

return;

}

for (int i = 0; i < N; i++) {

if (v[i])

continue;

v[i] = true;

b[cnt] = a[i];

perm(cnt + 1);

v[i] = false;

}

}

static void comb(int cnt, int start) {

if (cnt == R) {

System.out.println(Arrays.toString(b));

C++;

return;

}

for (int i = start; i < N; i++) {

b[cnt] = a[i];

comb(cnt + 1, i + 1);

}

}

public static void main(String[] args) throws Exception {

C = 0;

// perm(0); // 순서중요

comb(0, 0); // 순서무관

System.out.println(C);

}

}