Problem p03202 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <bits/stdc++.h>

#define rep(i, n) for (int i = 0; i < int(n); i++)
#define rrep(i, n) for (int i = int(n) - 1; i >= 0; i--)
#define reps(i, n) for (int i = 1; i <= int(n); i++)
#define rreps(i, n) for (int i = int(n); i >= 1; i--)
#define repc(i, n) for (int i = 0; i <= int(n); i++)
#define rrepc(i, n) for (int i = int(n); i >= 0; i--)
#define repi(i, a, b) for (int i = int(a); i < int(b); i++)
#define repic(i, a, b) for (int i = int(a); i <= int(b); i++)
#define each(x, y) for (auto &x : y)
#define all(a) (a).begin(), (a).end()
#define bit(b) (1ll << (b))

using namespace std;

using i32 = int;
using i64 = long long;
using u64 = unsigned long long;
using f80 = long double;
using vi32 = vector<i32>;
using vi64 = vector<i64>;
using vu64 = vector<u64>;
using vf80 = vector<f80>;
using vstr = vector<string>;

inline void yes() {
  cout << "Yes" << '\n';
  exit(0);
}
inline void no() {
  cout << "No" << '\n';
  exit(0);
}
inline i64 gcd(i64 a, i64 b) {
  if (min(a, b) == 0)
    return max(a, b);
  if (a % b == 0)
    return b;
  return gcd(b, a % b);
}
inline i64 lcm(i64 a, i64 b) { return a / gcd(a, b) * b; }
inline u64 xorshift() {
  static u64 x = 88172645463325252ull;
  x = x ^ (x << 7);
  return x = x ^ (x >> 9);
}
void solve();
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout << fixed << setprecision(16);
  solve();
  return 0;
}
template <typename T>
class pqasc : public priority_queue<T, vector<T>, greater<T>> {};
template <typename T>
class pqdesc : public priority_queue<T, vector<T>, less<T>> {};
template <typename T> inline void amax(T &x, T y) {
  if (x < y)
    x = y;
}
template <typename T> inline void amin(T &x, T y) {
  if (x > y)
    x = y;
}
template <typename T> inline T power(T x, i64 n, T e = 1) {
  T r = e;
  while (n > 0) {
    if (n & 1)
      r *= x;
    x *= x;
    n >>= 1;
  }
  return r;
}
template <typename T> istream &operator>>(istream &is, vector<T> &v) {
  each(x, v) is >> x;
  return is;
}
template <typename T> ostream &operator<<(ostream &os, vector<T> &v) {
  rep(i, v.size()) {
    if (i)
      os << ' ';
    os << v[i];
  }
  return os;
}
template <typename T, typename S>
istream &operator>>(istream &is, pair<T, S> &p) {
  is >> p.first >> p.second;
  return is;
}
template <typename T, typename S>
ostream &operator<<(ostream &os, pair<T, S> &p) {
  os << p.first << ' ' << p.second;
  return os;
}

int N;
vector<int> a;

bool check(int x) {
  map<int, int> ma;
  for (int i = 1; i < N; i++) {
    if (a[i - 1] < a[i]) {
      continue;
    }
    int idx = a[i];
    auto it = ma.upper_bound(idx);
    while (it != ma.end()) {
      ma.erase(it++);
    }
    while (true) {
      ma[idx]++;
      if (ma[idx] < x) {
        break;
      }
      if (idx == 1)
        return false;
      ma.erase(idx);
      idx--;
    }
  }
  return true;
}

void solve() {
  cin >> N;
  a.resize(N);
  cin >> a;
  int ok = 200000, ng = 0;
  while (ok - ng > 1) {
    int md = (ok + ng) / 2;
    check(md) ? (ok = md) : (ng = md);
  }
  cout << ok << '\n';
}


Fixed submission:
#include <bits/stdc++.h>

#define rep(i, n) for (int i = 0; i < int(n); i++)
#define rrep(i, n) for (int i = int(n) - 1; i >= 0; i--)
#define reps(i, n) for (int i = 1; i <= int(n); i++)
#define rreps(i, n) for (int i = int(n); i >= 1; i--)
#define repc(i, n) for (int i = 0; i <= int(n); i++)
#define rrepc(i, n) for (int i = int(n); i >= 0; i--)
#define repi(i, a, b) for (int i = int(a); i < int(b); i++)
#define repic(i, a, b) for (int i = int(a); i <= int(b); i++)
#define each(x, y) for (auto &x : y)
#define all(a) (a).begin(), (a).end()
#define bit(b) (1ll << (b))

using namespace std;

using i32 = int;
using i64 = long long;
using u64 = unsigned long long;
using f80 = long double;
using vi32 = vector<i32>;
using vi64 = vector<i64>;
using vu64 = vector<u64>;
using vf80 = vector<f80>;
using vstr = vector<string>;

inline void yes() {
  cout << "Yes" << '\n';
  exit(0);
}
inline void no() {
  cout << "No" << '\n';
  exit(0);
}
inline i64 gcd(i64 a, i64 b) {
  if (min(a, b) == 0)
    return max(a, b);
  if (a % b == 0)
    return b;
  return gcd(b, a % b);
}
inline i64 lcm(i64 a, i64 b) { return a / gcd(a, b) * b; }
inline u64 xorshift() {
  static u64 x = 88172645463325252ull;
  x = x ^ (x << 7);
  return x = x ^ (x >> 9);
}
void solve();
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout << fixed << setprecision(16);
  solve();
  return 0;
}
template <typename T>
class pqasc : public priority_queue<T, vector<T>, greater<T>> {};
template <typename T>
class pqdesc : public priority_queue<T, vector<T>, less<T>> {};
template <typename T> inline void amax(T &x, T y) {
  if (x < y)
    x = y;
}
template <typename T> inline void amin(T &x, T y) {
  if (x > y)
    x = y;
}
template <typename T> inline T power(T x, i64 n, T e = 1) {
  T r = e;
  while (n > 0) {
    if (n & 1)
      r *= x;
    x *= x;
    n >>= 1;
  }
  return r;
}
template <typename T> istream &operator>>(istream &is, vector<T> &v) {
  each(x, v) is >> x;
  return is;
}
template <typename T> ostream &operator<<(ostream &os, vector<T> &v) {
  rep(i, v.size()) {
    if (i)
      os << ' ';
    os << v[i];
  }
  return os;
}
template <typename T, typename S>
istream &operator>>(istream &is, pair<T, S> &p) {
  is >> p.first >> p.second;
  return is;
}
template <typename T, typename S>
ostream &operator<<(ostream &os, pair<T, S> &p) {
  os << p.first << ' ' << p.second;
  return os;
}

int N;
vector<int> a;

bool check(int x) {
  map<int, int> ma;
  for (int i = 1; i < N; i++) {
    if (a[i - 1] < a[i]) {
      continue;
    }
    if (x == 1)
      return false;
    int idx = a[i];
    auto it = ma.upper_bound(idx);
    while (it != ma.end()) {
      ma.erase(it++);
    }
    while (true) {
      ma[idx]++;
      if (ma[idx] < x) {
        break;
      }
      if (idx == 1)
        return false;
      ma.erase(idx);
      idx--;
    }
  }
  return true;
}

void solve() {
  cin >> N;
  a.resize(N);
  cin >> a;
  int ok = 200000, ng = 0;
  while (ok - ng > 1) {
    int md = (ok + ng) / 2;
    check(md) ? (ok = md) : (ng = md);
  }
  cout << ok << '\n';
}