Submission #387944

#	Time	Username	Problem	Language	Result	Execution time	Memory
387944		nikatamliani	JJOOII 2 (JOI20_ho_t2)	C++14	100 / 100	8 ms	3292 KiB

ho_t2

#include <bits/stdc++.h>
#define ll long long
using namespace std;
const ll N = 5e5+5, oo = 1e18+10;
ll n, k, cnt[N];
string s;
ll sum(ll l, ll r) {
	return cnt[r] - cnt[l - 1];
}
int main() {
	ios::sync_with_stdio(0); cin.tie(0);
	cin >> n >> k >> s;
	vector<int> I, J;
	for(int i = 0; i < n; ++i) {
		if(s[i] == 'J') {
			J.push_back(i);
		}
		if(s[i] == 'I') {
			I.push_back(i);
		}
		cnt[i] = cnt[i - 1] + (s[i] == 'O');
	}
	ll ans = oo;
	for(int i = k - 1, j = 0; i < (int)J.size(); ++i) {
		while(j+k <= (int)I.size() && (I[j] < J[i] || sum(J[i], I[j]) < k)) ++j;
		if(j+k <= (int)I.size() && sum(J[i], I[j]) >= k) {
			ll lft = J[i] - J[i - k + 1] + 1 - k;
			ll rgh = I[j+k-1] - I[j] + 1 - k;
			ll mid = I[j] - J[i] - 1 - k;
			ans = min(ans, lft + mid + rgh);
		} 
	}
	if(ans == oo) {
		ans = -1;
	}
	cout << ans << endl;
}

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