Problem p02953 (C++)

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

using namespace std;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<VVI> VVVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef vector<PII> VPII;
typedef long long LL;
typedef priority_queue<int> PQ_DESC;
typedef priority_queue<int, vector<int>, greater<int>> PQ_ASC;
typedef priority_queue<PII> PQ_DESC_PII;
typedef priority_queue<PII, vector<PII>, greater<PII>> PQ_ASC_PII;
typedef vector<LL> VLL;
typedef vector<VLL> VVLL;
typedef vector<VVLL> VVVLL;

#define SORT_ASC(c) sort((c).begin(), (c).end())
#define SORT_DESC(c)                                                           \
  sort((c).begin(), (c).end(), greater<typeof((c).begin())>())

#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define REP(i, n) FOR(i, 0, n)
#define SIZE(a) int((a).size())

const double EPS = 1e-10;
const double PI = acos(-1.0);
const int INT_LARGE = 1000000100;

// debug func
template <typename T> void vecprint(vector<T> v) {
  for (auto x : v) {
    cerr << x << " ";
  }
  cerr << endl;
}

template <typename T> void vecvecprint(vector<vector<T>> v) {
  for (auto x : v) {
    REP(i, x.size() - 1) { cerr << x[i] << " "; }
    cerr << x[x.size() - 1] << endl;
  }
}

template <typename T> void pqprint(priority_queue<T> q) {
  while (!q.empty()) {
    cerr << q.top() << " ";
    q.pop();
  }
  cerr << endl;
}

template <typename T> void qprint(queue<T> q) {
  while (!q.empty()) {
    cerr << q.front() << " ";
    q.pop();
  }
  cerr << endl;
}

template <typename T> void vecqprint(vector<queue<T>> v) {
  for (int i = 0; i < v.size(); i++) {
    qprint(v[i]);
  }
}

template <typename Iterator>
inline bool next_combination(const Iterator first, Iterator k,
                             const Iterator last) {
  /* Credits: Thomas Draper */
  if ((first == last) || (first == k) || (last == k))
    return false;
  Iterator itr1 = first;
  Iterator itr2 = last;
  ++itr1;
  if (last == itr1)
    return false;
  itr1 = last;
  --itr1;
  itr1 = k;
  --itr2;
  while (first != itr1) {
    if (*--itr1 < *itr2) {
      Iterator j = k;
      while (!(*itr1 < *j))
        ++j;
      iter_swap(itr1, j);
      ++itr1;
      ++j;
      itr2 = k;
      rotate(itr1, j, last);
      while (last != j) {
        ++j;
        ++itr2;
      }
      rotate(k, itr2, last);
      return true;
    }
  }
  rotate(first, k, last);
  return false;
}

inline double get_time_sec(void) {
  return static_cast<double>(chrono::duration_cast<chrono::nanoseconds>(
                                 chrono::steady_clock::now().time_since_epoch())
                                 .count()) /
         1000000000;
}

VI vi;

int main(void) {
  int n;
  cin >> n;
  vi = VI(n, 0);
  REP(i, n) cin >> vi[i];
  for (int i = n - 1; i > 0; i--) {
    cerr << "i: " << i << ", ";
    vecprint(vi);
    if (vi[i - 1] - vi[i] > 1) {
      cout << "No" << endl;
      return 0;
    }
    if (vi[i - 1] - vi[i] == 1) {
      vi[i - 1]--;
      continue;
    }
  }
  cout << "Yes" << endl;
}

Fixed submission:
#include "bits/stdc++.h"

using namespace std;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<VVI> VVVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef vector<PII> VPII;
typedef long long LL;
typedef priority_queue<int> PQ_DESC;
typedef priority_queue<int, vector<int>, greater<int>> PQ_ASC;
typedef priority_queue<PII> PQ_DESC_PII;
typedef priority_queue<PII, vector<PII>, greater<PII>> PQ_ASC_PII;
typedef vector<LL> VLL;
typedef vector<VLL> VVLL;
typedef vector<VVLL> VVVLL;

#define SORT_ASC(c) sort((c).begin(), (c).end())
#define SORT_DESC(c)                                                           \
  sort((c).begin(), (c).end(), greater<typeof((c).begin())>())

#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define REP(i, n) FOR(i, 0, n)
#define SIZE(a) int((a).size())

const double EPS = 1e-10;
const double PI = acos(-1.0);
const int INT_LARGE = 1000000100;

// debug func
template <typename T> void vecprint(vector<T> v) {
  for (auto x : v) {
    cerr << x << " ";
  }
  cerr << endl;
}

template <typename T> void vecvecprint(vector<vector<T>> v) {
  for (auto x : v) {
    REP(i, x.size() - 1) { cerr << x[i] << " "; }
    cerr << x[x.size() - 1] << endl;
  }
}

template <typename T> void pqprint(priority_queue<T> q) {
  while (!q.empty()) {
    cerr << q.top() << " ";
    q.pop();
  }
  cerr << endl;
}

template <typename T> void qprint(queue<T> q) {
  while (!q.empty()) {
    cerr << q.front() << " ";
    q.pop();
  }
  cerr << endl;
}

template <typename T> void vecqprint(vector<queue<T>> v) {
  for (int i = 0; i < v.size(); i++) {
    qprint(v[i]);
  }
}

template <typename Iterator>
inline bool next_combination(const Iterator first, Iterator k,
                             const Iterator last) {
  /* Credits: Thomas Draper */
  if ((first == last) || (first == k) || (last == k))
    return false;
  Iterator itr1 = first;
  Iterator itr2 = last;
  ++itr1;
  if (last == itr1)
    return false;
  itr1 = last;
  --itr1;
  itr1 = k;
  --itr2;
  while (first != itr1) {
    if (*--itr1 < *itr2) {
      Iterator j = k;
      while (!(*itr1 < *j))
        ++j;
      iter_swap(itr1, j);
      ++itr1;
      ++j;
      itr2 = k;
      rotate(itr1, j, last);
      while (last != j) {
        ++j;
        ++itr2;
      }
      rotate(k, itr2, last);
      return true;
    }
  }
  rotate(first, k, last);
  return false;
}

inline double get_time_sec(void) {
  return static_cast<double>(chrono::duration_cast<chrono::nanoseconds>(
                                 chrono::steady_clock::now().time_since_epoch())
                                 .count()) /
         1000000000;
}

VI vi;

int main(void) {
  int n;
  cin >> n;
  vi = VI(n, 0);
  REP(i, n) cin >> vi[i];
  for (int i = n - 1; i > 0; i--) {
    // cerr << "i: " << i << ", ";
    // vecprint(vi);
    if (vi[i - 1] - vi[i] > 1) {
      cout << "No" << endl;
      return 0;
    }
    if (vi[i - 1] - vi[i] == 1) {
      vi[i - 1]--;
      continue;
    }
  }
  cout << "Yes" << endl;
}