Submission #3599234

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Source Code Expand

#include <algorithm>
#include <cmath>
#include <chrono>
#include <cstdio>
#include <ctime>
#include <iostream>
#include <random>
#include <string>
#include <vector>
using namespace std;

#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
/*---------------------------------------*/

const int MAX = 300000;
const int MOD = 998244353;

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  // freopen("input.txt", "r", stdin);

  int n; cin >> n;

  vector<int> a(n);
  vector<int> length(MAX+1, 0);
  int first1 = 0, max_num = 0;
  bool start1 = false;
  REP(i, n) {
    cin >> a[i];
    max_num = max(max_num, a[i]);
    if (a[i] == 1) {
      ++length[1];
      if (start1) {
        first1 = i;
        start1 = false;
      }
    } else if (first1 == 0) {
      start1 = true;
    }
  }
  vector<int> b(n+1, 0);
  int i = 0;
  FOR(j, first1, n) {
    b[i] = a[j];
    ++i;
  }
  FOR(j, 0, first1) {
    b[i] = a[j];
    ++i;
  }

  long long ans = 1;
  vector<bool> already(MAX+1, false);
  int nexti;
  // vector<int> p(n, 0);
  // p[0] = 1;
  for (int i = length[1]; i < n; i = nexti) {
    if (already[b[i]]) {
      cout << 0 << "\n";
      return 0;
    } else {
      already[b[i]] = true;
    }

    nexti = i + 1;
    while (b[nexti] == b[i]) ++nexti;
    if (nexti - i > length[1]) {
      cout << 0 << "\n";
      return 0;
    }
    length[b[i]] = nexti - i;

    if (b[i-1] > b[i]) {
      // p[i] = b[i];
      if (b[nexti] > b[nexti-1] && length[b[i]] != length[1]) {
        cout << 0 << "\n";
        return 0;
      }
    } else if (b[nexti] > b[nexti-1]) {
      // p[nexti-length[i]] = b[i];
    } else {
      ans *= (length[1] - (length[b[i]]) + 1) % MOD;
    }
  }

  FOR (i, 2, max_num+1) {
    if (!already[i]) {
      bool to_next = false;
      int last = 0, temp = 0, loop_count = 0, temp_loop_count = 0;
      for(int j = 0; j < n; j += length[b[j]]) {
        if (b[j] < i) {
          if (to_next) {
            temp += length[b[j]];
            ++temp_loop_count;
          } else {
            last += length[b[j]];
            ++loop_count;
          }
        } else if (to_next) {
          last = max(last, temp);
          if (last == temp) {
            loop_count = temp_loop_count;
          }
          temp = 0;
        } else {
          to_next = true;
        }
      }
      last -= length[1] + loop_count - 1;
      last %= MOD;
      ans *= last;
    }
  }

  for (int i = n - max_num; i > 1; --i) {
    ans *= i;
    ans %= MOD;
  }

  cout << ans << "\n";
  return 0;
}

Submission Info

Judge Result