Problem p02603 (C++) — buggy submission, verdict: Runtime Error

#include <bits/stdc++.h>
#define _GLIBCXX_DEBUG
using namespace std;
using ll = long long;
using ld = long double;
using V = vector<int>;
using Vll = vector<ll>;
using Vld = vector<ld>;
using Vbo = vector<bool>;
using VV = vector<V>;
using VVll = vector<Vll>;
using VVld = vector<Vld>;
using VVbo = vector<Vbo>;
using VVV = vector<VV>;
using VVVll = vector<VVll>;
using P = pair<int, int>;
using Pll = pair<ll, ll>;
using Pld = pair<ld, ld>;
#define rep2(i, m, n) for (int i = (m); i < (n); ++i)
#define drep2(i, m, n) for (int i = (m)-1; i >= (n); --i)
#define rep(i, n) rep2(i, 0, n)
#define drep(i, n) drep2(i, n, 0)
#define all(a) (a).begin(), (a).end()
struct fast_ios {
  fast_ios() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(20);
  };
} fast_ios_;
template <typename T> inline int sz(T &x) { return x.size(); }
template <typename T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <typename T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <typename T1, typename T2>
istream &operator>>(istream &is, pair<T1, T2> &p) {
  is >> p.first >> p.second;
  return is;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) {
  os << '(' << p.first << ", " << p.second << ')';
  return os;
}
template <typename T> istream &operator>>(istream &is, vector<T> &v) {
  for (auto &e : v)
    is >> e;
  return is;
}
template <typename T> ostream &operator<<(ostream &os, const vector<T> &v) {
  for (auto &e : v)
    os << e << ' ';
  return os;
}
template <typename T> inline int count_between(vector<T> &a, T l, T r) {
  return lower_bound(all(a), r) - lower_bound(all(a), l);
} // [l, r)
inline int fLog2(const int x) {
  assert(x > 0);
  return 31 - __builtin_clz(x);
} // floor(log2(x))
inline int fLog2(const ll x) {
  assert(x > 0);
  return 63 - __builtin_clzll(x);
}
inline int cLog2(const int x) {
  assert(x > 0);
  return (x == 1) ? 0 : 32 - __builtin_clz(x - 1);
} // ceil(log2(x))
inline int cLog2(const ll x) {
  assert(x > 0);
  return (x == 1) ? 0 : 64 - __builtin_clzll(x - 1);
}
inline int popcount(const int x) { return __builtin_popcount(x); }
inline int popcount(const ll x) { return __builtin_popcountll(x); }
const int INF = 1 << 30;
const ll INFll = 1ll << 62;
const ld EPS = 1e-10;
const ld PI = acos(-1.0);
// const int MOD  = int(1e9)+7;
// const int MOD  = 998244353;

int main() {
  ll n;
  cin >> n;
  Vll a(n);
  cin >> a;

  Vll b(n - 1);
  rep(i, n - 1) b[i] = a[i + 1] - a[i];

  Vll c = {b[0]};
  rep2(i, 1, n - 1) {
    if (c.back() * b[i] >= 0)
      c.back() += b[i];
    else
      c.push_back(b[i]);
  }

  int k = sz(c);
  Vll d(k + 1);
  d[0] = a[0];
  rep(i, k) d[i + 1] = d[i] + c[i];

  ll x = 1000;
  ll y = 0;
  rep(i, k) {
    if (d[i + 1] > d[i]) {
      y += x / d[i];
      x -= x / d[i] * d[i];
    } else {
      x += y * d[i];
      y = 0;
    }
  }

  ll ans = x + y * a.back();
  cout << ans << '\\n';
  return 0;
}


Error: -6
munmap_chunk(): invalid pointer


Fixed submission:

#include <bits/stdc++.h>
#define _GLIBCXX_DEBUG
using namespace std;
using ll = long long;
using ld = long double;
using V = vector<int>;
using Vll = vector<ll>;
using Vld = vector<ld>;
using Vbo = vector<bool>;
using VV = vector<V>;
using VVll = vector<Vll>;
using VVld = vector<Vld>;
using VVbo = vector<Vbo>;
using VVV = vector<VV>;
using VVVll = vector<VVll>;
using P = pair<int, int>;
using Pll = pair<ll, ll>;
using Pld = pair<ld, ld>;
#define rep2(i, m, n) for (int i = (m); i < (n); ++i)
#define drep2(i, m, n) for (int i = (m)-1; i >= (n); --i)
#define rep(i, n) rep2(i, 0, n)
#define drep(i, n) drep2(i, n, 0)
#define all(a) (a).begin(), (a).end()
struct fast_ios {
  fast_ios() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(20);
  };
} fast_ios_;
template <typename T> inline int sz(T &x) { return x.size(); }
template <typename T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <typename T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <typename T1, typename T2>
istream &operator>>(istream &is, pair<T1, T2> &p) {
  is >> p.first >> p.second;
  return is;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) {
  os << '(' << p.first << ", " << p.second << ')';
  return os;
}
template <typename T> istream &operator>>(istream &is, vector<T> &v) {
  for (auto &e : v)
    is >> e;
  return is;
}
template <typename T> ostream &operator<<(ostream &os, const vector<T> &v) {
  for (auto &e : v)
    os << e << ' ';
  return os;
}
template <typename T> inline int count_between(vector<T> &a, T l, T r) {
  return lower_bound(all(a), r) - lower_bound(all(a), l);
} // [l, r)
inline int fLog2(const int x) {
  assert(x > 0);
  return 31 - __builtin_clz(x);
} // floor(log2(x))
inline int fLog2(const ll x) {
  assert(x > 0);
  return 63 - __builtin_clzll(x);
}
inline int cLog2(const int x) {
  assert(x > 0);
  return (x == 1) ? 0 : 32 - __builtin_clz(x - 1);
} // ceil(log2(x))
inline int cLog2(const ll x) {
  assert(x > 0);
  return (x == 1) ? 0 : 64 - __builtin_clzll(x - 1);
}
inline int popcount(const int x) { return __builtin_popcount(x); }
inline int popcount(const ll x) { return __builtin_popcountll(x); }
const int INF = 1 << 30;
const ll INFll = 1ll << 62;
const ld EPS = 1e-10;
const ld PI = acos(-1.0);
// const int MOD  = int(1e9)+7;
// const int MOD  = 998244353;

int main() {
  ll n;
  cin >> n;
  Vll a(n);
  cin >> a;

  Vll b(n - 1);
  rep(i, n - 1) b[i] = a[i + 1] - a[i];

  Vll c = {b[0]};
  rep2(i, 1, n - 1) {
    if (c.back() * b[i] >= 0)
      c.back() += b[i];
    else
      c.push_back(b[i]);
  }

  Vll d = {a[0]};
  int k = sz(c);
  rep(i, k) d[i + 1] = d[i] + c[i];

  ll x = 1000;
  ll y = 0;
  rep(i, k) {
    if (d[i + 1] > d[i]) {
      y += x / d[i];
      x -= x / d[i] * d[i];
    } else {
      x += y * d[i];
      y = 0;
    }
  }

  ll ans = x + y * a.back();
  cout << ans << '\\n';
  return 0;
}