Problem p03752 (C++)

Buggy submission (status: Runtime Error):
/*~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=
* * WRITER:kakitamasziru/OxOmisosiru * *
~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=*/
#ifdef LOCAL_JUDGE
#define _GLIBCXX_DEBUG // FOR THE DEBUG! COMMENT OUT THIS WHEN SUBMITTING!
#endif
#include <algorithm> // min, max, swap, sort, reverse, lower_bound, upper_bound
#include <cstdint>   // int64_t, int*_t
#include <iomanip>
#include <iostream> // cout, endl, cin
#include <limits>   //setprecision
#include <string>   // string, to_string, stoi
#include <tuple>    // tuple, make_tuple
#include <utility>  // pair, make_pair
#include <vector>   // vector
// #include <cstdio> // printf
#include <bitset> // bitset
#include <cmath>  //abs,,,
#include <deque>  // deque
#include <map>    // map
#include <math.h> //pow,,,
#include <queue>  // queue, priority_queue
#include <set>    // set
#include <stack>  // stack
// It is so troublesome that I include bits/stdc++.h !
using namespace std;

template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
const long long INF = 1001001001001001;
const long long MOD = 1000000007;
typedef pair<int, int> P;
// NのM乗を求める(繰り返し二乗法)
long long mod_pow(long long N, long long M) {
  if (M == 0)
    return 1;
  long long res = mod_pow((N * N) % MOD, M / 2);
  // 最下位ビット(*N)が1の時は単独でNをかける
  if (M & 1)
    res = (res * N) % MOD;

  return res %= MOD;
}
long long nCr(long long n, long long r) {
  long long A = 1, B = 1;
  // Aが分子Bが1/r!
  for (long long i = n - r + 1; i <= n; i++) {
    A = A * i % MOD;
  }
  for (long long i = 1; i <= r; i++) {
    B = B * i % MOD;
  }
  B = mod_pow(B, MOD - 2);
  B %= MOD;
  // Bは割るのではなく掛ける
  return (A * B) % MOD;
}

long long gcd(long long a, long long b) {
  if (b == 0)
    return a;
  else
    return gcd(b, a % b);
}

long long lcm(long long a, long long b) { return a * b / gcd(a, b); }

long long A, B;
bool ok(long long key, long long index) {
  string S = to_string(index);
  long long nagasa = S.size();
  if (index * A + nagasa * B > key)
    return true;
  else if (index * A + nagasa * B <= key)
    return false;
}
long long binary_search(long long key, long long size) {
  // left,right,midはいずれもindex
  long long left = -1, right = size;
  while (right - left > 1) {
    long long mid = left + (right - left) / 2;
    long long hantei = ok(key, mid);
    if (hantei)
      right = mid;
    else
      left = mid;
  }
  if (left == -1)
    return 0;
  return left;
}

int main() {
  int N, K;
  cin >> N >> K;
  vector<long long> retu(N);
  for (int i = 0; i < N; i++)
    cin >> retu.at(i);
  long long ans = INF;
  long long nowans = 0;

  for (int bit = 0; bit < (1 << N); bit++) {
    bitset<6> B(bit);
    int count = 0;
    for (int j = 0; j < N; j++) {
      if (B.test(j))
        count++;
    }
    if (count < K)
      continue;
    long long maxi = 0;
    for (int j = 0; j < N; j++) {
      maxi = max(maxi, retu.at(j));
      if (B.test(j)) {
        if (retu.at(j) > maxi) {
          maxi = retu.at(j);
        } else {
          nowans += maxi - retu.at(j);
          maxi++;
        }
      }
    }
    ans = min(ans, nowans);
    nowans = 0;
    maxi = 0;
  }

  cout << ans << endl;

  // PLEASE GIVE ME THE "ACCEPTED" !
}


Fixed submission:
/*~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=
* * WRITER:kakitamasziru/OxOmisosiru * *
~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=*/
#ifdef LOCAL_JUDGE
#define _GLIBCXX_DEBUG // FOR THE DEBUG! COMMENT OUT THIS WHEN SUBMITTING!
#endif
#include <algorithm> // min, max, swap, sort, reverse, lower_bound, upper_bound
#include <cstdint>   // int64_t, int*_t
#include <iomanip>
#include <iostream> // cout, endl, cin
#include <limits>   //setprecision
#include <string>   // string, to_string, stoi
#include <tuple>    // tuple, make_tuple
#include <utility>  // pair, make_pair
#include <vector>   // vector
// #include <cstdio> // printf
#include <bitset> // bitset
#include <cmath>  //abs,,,
#include <deque>  // deque
#include <map>    // map
#include <math.h> //pow,,,
#include <queue>  // queue, priority_queue
#include <set>    // set
#include <stack>  // stack
// It is so troublesome that I include bits/stdc++.h !
using namespace std;

template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
const long long INF = 1001001001001001;
const long long MOD = 1000000007;
typedef pair<int, int> P;
// NのM乗を求める(繰り返し二乗法)
long long mod_pow(long long N, long long M) {
  if (M == 0)
    return 1;
  long long res = mod_pow((N * N) % MOD, M / 2);
  // 最下位ビット(*N)が1の時は単独でNをかける
  if (M & 1)
    res = (res * N) % MOD;

  return res %= MOD;
}
long long nCr(long long n, long long r) {
  long long A = 1, B = 1;
  // Aが分子Bが1/r!
  for (long long i = n - r + 1; i <= n; i++) {
    A = A * i % MOD;
  }
  for (long long i = 1; i <= r; i++) {
    B = B * i % MOD;
  }
  B = mod_pow(B, MOD - 2);
  B %= MOD;
  // Bは割るのではなく掛ける
  return (A * B) % MOD;
}

long long gcd(long long a, long long b) {
  if (b == 0)
    return a;
  else
    return gcd(b, a % b);
}

long long lcm(long long a, long long b) { return a * b / gcd(a, b); }

long long A, B;
bool ok(long long key, long long index) {
  string S = to_string(index);
  long long nagasa = S.size();
  if (index * A + nagasa * B > key)
    return true;
  else if (index * A + nagasa * B <= key)
    return false;
}
long long binary_search(long long key, long long size) {
  // left,right,midはいずれもindex
  long long left = -1, right = size;
  while (right - left > 1) {
    long long mid = left + (right - left) / 2;
    long long hantei = ok(key, mid);
    if (hantei)
      right = mid;
    else
      left = mid;
  }
  if (left == -1)
    return 0;
  return left;
}

int main() {
  int N, K;
  cin >> N >> K;
  vector<long long> retu(N);
  for (int i = 0; i < N; i++)
    cin >> retu.at(i);
  long long ans = INF;
  long long nowans = 0;

  for (int bit = 0; bit < (1 << N); bit++) {
    bitset<15> B(bit);
    int count = 0;
    for (int j = 0; j < N; j++) {
      if (B.test(j))
        count++;
    }
    if (count < K)
      continue;
    long long maxi = 0;
    for (int j = 0; j < N; j++) {
      maxi = max(maxi, retu.at(j));
      if (B.test(j)) {
        if (retu.at(j) > maxi) {
          maxi = retu.at(j);
        } else {
          nowans += maxi - retu.at(j);
          maxi++;
        }
      }
    }
    ans = min(ans, nowans);
    nowans = 0;
    maxi = 0;
  }

  cout << ans << endl;

  // PLEASE GIVE ME THE "ACCEPTED" !
}