Problem p03309 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>
#pragma GCC optimize("Ofast,unroll-loops,no-stack-protector")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
using namespace std;
typedef long long ll;
typedef double lf;
typedef pair<ll, ll> ii;
#define REP(i, n) for (int i = 0; i < n; i++)
#define REP1(i, n) for (ll i = 1; i <= n; i++)
#define FOR(i, j, n, m) for (int i = j; i < n; i += m)
#define RST(i, n) memset(i, n, sizeof i)
#define SZ(a) (int)a.size()
#define ALL(a) a.begin(), a.end()
#define X first
#define Y second
#define mkp make_pair
#define pb push_back
#define pob pop_back
#ifdef cold66
#define debug(...)                                                             \
  do {                                                                         \
    fprintf(stderr, "%s - %d (%s) = ", __PRETTY_FUNCTION__, __LINE__,          \
            #__VA_ARGS__);                                                     \
    _do(__VA_ARGS__);                                                          \
  } while (0)
template <typename T> void _do(T &&_x) { cerr << _x << endl; }
template <typename T, typename... S> void _do(T &&_x, S &&..._t) {
  cerr << _x << " ,";
  _do(_t...);
}
template <typename _a, typename _b>
ostream &operator<<(ostream &_s, const pair<_a, _b> &_p) {
  return _s << "(" << _p.F << "," << _p.S << ")";
}
template <typename It> ostream &_OUTC(ostream &_s, It _ita, It _itb) {
  _s << "{";
  for (It _it = _ita; _it != _itb; _it++) {
    _s << (_it == _ita ? "" : ",") << *_it;
  }
  _s << "}";
  return _s;
}
template <typename _a> ostream &operator<<(ostream &_s, vector<_a> &_c) {
  return _OUTC(_s, ALL(_c));
}
template <typename _a> ostream &operator<<(ostream &_s, set<_a> &_c) {
  return _OUTC(_s, ALL(_c));
}
template <typename _a, typename _b>
ostream &operator<<(ostream &_s, map<_a, _b> &_c) {
  return _OUTC(_s, ALL(_c));
}
template <typename _t> void pary(_t _a, _t _b) {
  _OUTC(cerr, _a, _b);
  cerr << endl;
}
#define IOS()
#else
#define debug(...)
#define pary(...)
#define endl '\n'
#define IOS()                                                                  \
  ios_base::sync_with_stdio(0);                                                \
  cin.tie(0);
#endif // cold66
//}

template <class T> inline bool chkmax(T &a, const T &b) {
  return b > a ? a = b, true : false;
}
template <class T> inline bool chkmin(T &a, const T &b) {
  return b < a ? a = b, true : false;
}
template <class T> using MaxHeap = priority_queue<T>;
template <class T> using MinHeap = priority_queue<T, vector<T>, greater<T>>;

const ll MAXn = 1e5 + 5, MAXlg = __lg(MAXn) + 2;
const ll MOD = 1000000007;
const ll INF = (ll)1e18;

ll n;
ll d[MAXn], a[MAXn];
ll cal(ll b) {
  ll ret = 0;
  REP(i, n) ret += abs(a[i] - (b + i + 1));
  return ret;
}
int main() {
  IOS();
  cin >> n;
  REP(i, n) {
    cin >> a[i];
    d[i] = a[i] - i - 1;
  }
  sort(d, d + n);
  pary(d, d + n);
  ll tp = n / 2;
  debug(tp);
  ll ans = min(cal(d[tp]), cal(d[tp - 1]));
  cout << ans << endl;
}


Fixed submission:
#include <bits/stdc++.h>
#pragma GCC optimize("Ofast,unroll-loops,no-stack-protector")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
using namespace std;
typedef long long ll;
typedef double lf;
typedef pair<ll, ll> ii;
#define REP(i, n) for (int i = 0; i < n; i++)
#define REP1(i, n) for (ll i = 1; i <= n; i++)
#define FOR(i, j, n, m) for (int i = j; i < n; i += m)
#define RST(i, n) memset(i, n, sizeof i)
#define SZ(a) (int)a.size()
#define ALL(a) a.begin(), a.end()
#define X first
#define Y second
#define mkp make_pair
#define pb push_back
#define pob pop_back
#ifdef cold66
#define debug(...)                                                             \
  do {                                                                         \
    fprintf(stderr, "%s - %d (%s) = ", __PRETTY_FUNCTION__, __LINE__,          \
            #__VA_ARGS__);                                                     \
    _do(__VA_ARGS__);                                                          \
  } while (0)
template <typename T> void _do(T &&_x) { cerr << _x << endl; }
template <typename T, typename... S> void _do(T &&_x, S &&..._t) {
  cerr << _x << " ,";
  _do(_t...);
}
template <typename _a, typename _b>
ostream &operator<<(ostream &_s, const pair<_a, _b> &_p) {
  return _s << "(" << _p.F << "," << _p.S << ")";
}
template <typename It> ostream &_OUTC(ostream &_s, It _ita, It _itb) {
  _s << "{";
  for (It _it = _ita; _it != _itb; _it++) {
    _s << (_it == _ita ? "" : ",") << *_it;
  }
  _s << "}";
  return _s;
}
template <typename _a> ostream &operator<<(ostream &_s, vector<_a> &_c) {
  return _OUTC(_s, ALL(_c));
}
template <typename _a> ostream &operator<<(ostream &_s, set<_a> &_c) {
  return _OUTC(_s, ALL(_c));
}
template <typename _a, typename _b>
ostream &operator<<(ostream &_s, map<_a, _b> &_c) {
  return _OUTC(_s, ALL(_c));
}
template <typename _t> void pary(_t _a, _t _b) {
  _OUTC(cerr, _a, _b);
  cerr << endl;
}
#define IOS()
#else
#define debug(...)
#define pary(...)
#define endl '\n'
#define IOS()                                                                  \
  ios_base::sync_with_stdio(0);                                                \
  cin.tie(0);
#endif // cold66
//}

template <class T> inline bool chkmax(T &a, const T &b) {
  return b > a ? a = b, true : false;
}
template <class T> inline bool chkmin(T &a, const T &b) {
  return b < a ? a = b, true : false;
}
template <class T> using MaxHeap = priority_queue<T>;
template <class T> using MinHeap = priority_queue<T, vector<T>, greater<T>>;

const ll MAXn = 2e5 + 5, MAXlg = __lg(MAXn) + 2;
const ll MOD = 1000000007;
const ll INF = (ll)1e18;

ll n;
ll d[MAXn], a[MAXn];
ll cal(ll b) {
  ll ret = 0;
  REP(i, n) ret += abs(a[i] - (b + i + 1));
  return ret;
}
int main() {
  IOS();
  cin >> n;
  REP(i, n) {
    cin >> a[i];
    d[i] = a[i] - i - 1;
  }
  sort(d, d + n);
  pary(d, d + n);
  ll tp = n / 2;
  debug(tp);
  ll ans = min(cal(d[tp]), cal(d[tp - 1]));
  cout << ans << endl;
}