Submission #503844

#	Time	Username	Problem	Language	Result	Execution time	Memory
503844		cig32	JJOOII 2 (JOI20_ho_t2)	C++17	100 / 100	31 ms	5520 KiB

ho_t2

#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;
mt19937_64 rng((int)std::chrono::steady_clock::now().time_since_epoch().count());
const int MAXN = 3e5 + 10;
const int MOD = 1e9 + 7;
#define int long long

int rnd(int x, int y) { // random number generator
  int u= uniform_int_distribution<int>(x, y)(rng); return u;
}

void solve(int tc) {
  int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  int freq[n+1][3];
  for(int i=0; i<3; i++) freq[0][i] = 0;
  for(int i=0; i<n; i++) s[i] = (s[i] == 'J' ? '0' : (s[i] == 'O' ? '1' : '2'));
  for(int i=1; i<=n; i++) {
    for(int j=0; j<3; j++) {
      freq[i][j] = freq[i-1][j] + (s[i-1] == j + '0');
    }
  }
  int ans = 1e18;
  for(int i=1; i<=n; i++) {
    bool valid = 1;
    int lb = i, rb = n;
    while(lb<rb) {
      int mid = (lb+rb) >> 1;
      if(freq[mid][0] - freq[i-1][0] >= k) rb = mid;
      else lb = mid+1;
    }
    valid &= (freq[lb][0] - freq[i-1][0] == k);
    rb = n;
    int sto = lb;
    lb++;
    while(lb<rb) {
      int mid = (lb+rb) >> 1;
      if(freq[mid][1] - freq[sto][1] >= k) rb = mid;
      else lb = mid+1;
    }
    valid &= (freq[lb][1] - freq[sto][1] == k);
    rb = n;
    sto = lb;
    lb++;
    while(lb<rb) {
      int mid = (lb+rb) >> 1;
      if(freq[mid][2] - freq[sto][2] >= k) rb = mid;
      else lb = mid+1;
    }
    valid &= (freq[lb][2] - freq[sto][2] == k);
    if(valid) ans = min(ans, lb-i + 1 - 3*k);
  }
  cout << (ans == 1e18? -1 : ans);
}

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);
}

• Subtask 1: 1 / 1
• Subtask 2: 12 / 12
• Subtask 3: 87 / 87