Submission #941885

#	Time	Username	Problem	Language	Result	Execution time	Memory
941885		Litusiano	JJOOII 2 (JOI20_ho_t2)	C++17	100 / 100	55 ms	22736 KiB

ho_t2

#include<bits/stdc++.h>
using namespace std;
#define int long long

signed main(){
	int n; cin>>n;
	int k; cin>>k;
	string s; cin>>s;
	vector<vector<int>> pre(n+1, vector<int>(3,0));
	vector<vector<int>> dp(n+1, vector<int> (3,-1));
	vector<char> c = {'J','O','I'};
	for(int i = 0; i<n; i++){
		for(int j = 0; j<3; j++){
			pre[i+1][j] = pre[i][j] + (s[i] == c[j]);
		}
	}
	for(int i = 0; i<n; i++){
		for(int j = 0; j < 3; j++){
			int l = i; int r = n+1;
			while(r > l+1){
				int m = (l+r)/2;
				if(pre[m][j] - pre[i][j] >= k) r = m;
				else l = m;
			}	
			// cerr<<i<<" "<<j<<" "<<r<<" "<<r-i<<endl;
			if(r == n+1) dp[i][j] = -1;
			else dp[i][j] = r-i;
		}
	}
	int ans = LLONG_MAX;
	for(int i = 0; i<n; i++){
			bool ok = 1;
			if(s[i] != 'J') continue;
			int cur = i;
			for(int j = 0; j<3; j++){
				if(dp[cur][j] == -1){
					ok =0; break;
				}
				cur+=dp[cur][j];
			}
			if(ok)ans = min(ans,cur-i - 3*k);
	}
	if(ans == LLONG_MAX) ans = -1;
	cout<<ans<<endl;

}

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