Submission #390080

#	Time	Username	Problem	Language	Result	Execution time	Memory
390080		tushar_2658	JJOOII 2 (JOI20_ho_t2)	C++14	100 / 100	16 ms	4056 KiB

ho_t2

#include "bits/stdc++.h"
using namespace std;

const int maxn = 200005;

int n, k;
string s;
int pref[3][maxn];
int a[maxn];

int main(int argc, char const *argv[])
{
  ios::sync_with_stdio(false);
  cin.tie(0);

  cin >> n >> k;
  cin >> s;
  for(int i = 0; i < n; ++i){
    if(s[i] == 'J')a[i] = 0;
    else if(s[i] == 'O')a[i] = 1;
    else a[i] = 2;
    pref[a[i]][i] = 1;
  }
  for(int i = 0; i < 3; ++i){
    for(int j = 1; j < n; ++j){
      pref[i][j] += pref[i][j - 1];
    }
  }
  int ans = n + 1;
  for(int i = 0; i < n; ++i){
    if(s[i] != 'J')continue;
    int l = i, r = n - 1, ans1 = -1;
    while(l <= r){
      int mid = (l + r) >> 1;
      if(pref[0][mid] - pref[0][i - 1] >= k){
        ans1 = mid;
        r = mid - 1;
      }else {
        l = mid + 1;
      }
    }
    if(ans1 == -1)break; 
    int idx = ans1;
    l = idx, r = n - 1, ans1 = -1;
    while(l <= r){
      int mid = (l + r) >> 1;
      if(pref[1][mid] - pref[1][idx - 1] >= k){
        ans1 = mid;
        r = mid - 1;
      }else {
        l = mid + 1;
      }
    }
    if(ans1 == -1)break;
    idx = ans1;
    l = idx, r = n - 1, ans1 = -1;
    while(l <= r){
      int mid = (l + r) >> 1;
      if(pref[2][mid] - pref[2][idx - 1] >= k){
        ans1 = mid;
        r = mid - 1;
      }else {
        l = mid + 1;
      }
    }
    if(ans1 == -1)break;
    ans = min(ans, ans1 - i + 1 - (3 * k));
  }
  if(ans == n + 1)cout << "-1" << '\n';
  else cout << ans << '\n';

  return 0;
}

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