Submission #794109

#	Time	Username	Problem	Language	Result	Execution time	Memory
794109		cig32	스탬프 수집 (JOI16_ho_t2)	C++17	100 / 100	5 ms	4448 KiB

2016_ho_t2

#include "bits/stdc++.h"
using namespace std;
#define int long long
const int MAXN = 3e5 + 10;
const int MOD = 1e9 + 7;
mt19937_64 rng((int)std::chrono::steady_clock::now().time_since_epoch().count());
int rnd(int x, int y) {
  int u = uniform_int_distribution<int>(x, y)(rng); return u;
}
int bm(int b, int p) {
  if(p==0) return 1 % MOD;
  int r = bm(b, p >> 1);
  if(p&1) return (((r*r) % MOD) * b) % MOD;
  return (r*r) % MOD;
}
int inv(int b) { 
  return bm(b, MOD-2);
}
int fastlog(int x) {
  return (x == 0 ? -1 : 64 - __builtin_clzll(x) - 1);
}
void printcase(int i) { cout << "Case #" << i << ": "; }
int prej[MAXN];
int prejo[MAXN];
int sufi[MAXN];
int sufoi[MAXN];
int joi[MAXN];
void solve(int tc) {
  int n;
  cin >> n;
  char c[n+1];
  for(int i=1; i<=n; i++) cin >> c[i];
  for(int i=1; i<=n; i++) {
    prej[i] = prej[i-1] + (c[i] == 'J');
    prejo[i] = prejo[i-1] + (c[i] == 'O' ? prej[i-1] : 0);
    joi[i] = joi[i-1] + (c[i] == 'I' ? prejo[i-1] : 0);
  }
  for(int i=n; i>=1; i--) {
    sufi[i] = sufi[i+1] + (c[i] == 'I');
    sufoi[i] = sufoi[i+1] + (c[i] == 'O' ? sufi[i+1] : 0);
  }
  int ans = max(sufoi[1], prejo[n]);
  for(int i=1; i<n; i++) {
    ans = max(ans, prejo[i]);
    ans = max(ans, prej[i] * sufi[i+1]);
    ans = max(ans, sufoi[i+1]);
  }
  cout << ans + joi[n] << '\n';

}
int32_t main() {
  ios::sync_with_stdio(0); cin.tie(0);
  int t = 1; //cin >> t;
  for(int i=1; i<=t; i++) solve(i);
}
// 勿忘初衷

• Subtask 1: 30 / 30
• Subtask 2: 20 / 20
• Subtask 3: 50 / 50