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input/code.cpp: In function 'int main()':
input/code.cpp:32:7: warning: statement has no effect [-Wunused-value]
   d[-1];
   ~~~~^

#include<bits/stdc++.h>
using namespace std;

int n,k;
bool u[21];
long long d[21];

long long mn = 1e10;

void gen(int t, long long dd) {
  if(t == k) {
    mn = min(dd,mn);
    return;
  }
  for(int i = 0; i < n; i++) {
    if(u[i]) continue;
    u[i] = true;
    for(int j = 0; j < n; j++) {
      if(i == j || u[j]) continue;
      u[j] = true;
      gen(t+1,dd+abs(d[i]-d[j]));
    }
  }
}

int main() {
  cin >> n; cin >> k;
  for(int i = 0; i < 21; i++) u[i] = false;
  for(int i = 0; i < n; i++) {
    cin >> d[i];
  }
  d[-1];
  gen(0,0);
  cout << mn << "\n";
}

Test 1

Group: 1, 2, 3

Verdict: ACCEPTED

Test 2

Group: 1, 2, 3

Verdict: ACCEPTED

Test 3

Group: 3

Verdict: WRONG ANSWER

Test 4

Group: 3

Verdict: WRONG ANSWER

Test 5

Group: 1, 2, 3

Verdict: ACCEPTED

Test 6

Group: 2, 3

Verdict: WRONG ANSWER

Test 7

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 8

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 9

Group: 2, 3

Verdict: WRONG ANSWER

Test 10

Group: 2, 3

Verdict: WRONG ANSWER

Test 11

Group: 3

Verdict: WRONG ANSWER

Test 12

Group: 3

Verdict: WRONG ANSWER

Test 13

Group: 3

Verdict: WRONG ANSWER

Test 14

Group: 1, 2, 3

Verdict: ACCEPTED

Test 15

Group: 2, 3

Verdict: WRONG ANSWER

Test 16

Group: 3

Verdict: WRONG ANSWER

Test 17

Group: 3

Verdict: WRONG ANSWER

Test 18

Group: 2, 3

Verdict: WRONG ANSWER

Test 19

Group: 2, 3

Verdict: WRONG ANSWER

Test 20

Group: 3

Verdict: WRONG ANSWER