Submission #733497

#	Time	Username	Problem	Language	Result	Execution time	Memory
733497		pcc	JJOOII 2 (JOI20_ho_t2)	C++14	100 / 100	11 ms	3276 KiB

ho_t2

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

#define ll long long
#define pll pair<ll,ll>
#define fs first
#define sc second

const int inf = 1e9;

void solve(){
	int n,k;
	cin>>n>>k;
	string s;
	cin>>s;
	deque<char> dq;
	for(auto &i:s)dq.push_back(i);
	while(!dq.empty()&&dq.front() != 'J')dq.pop_front();
	while(!dq.empty()&&dq.back() != 'I')dq.pop_back();
	n = dq.size();
	int ans = inf;
	int jp[n+1] = {},ip[n+1] = {},op[n+1] = {};
	int pref = 0;
	int p = 0;
	//for(auto &i:dq)cout<<i;cout<<endl;
	for(int i = 0;i<n;i++){
		if(p<=i){
			p = i+1;
			if(dq[i] == 'J')pref = 1;
			else pref = 0;
		}
		while(p<n&&pref<k){
			if(dq[p] == 'J')pref++;
			p++;
		}
		if(pref<k)jp[i] = -1;
		else jp[i] = p;
		if(dq[i] == 'J')pref--;
	}
	pref = 0;
	p = 0;
	for(int i = 0;i<n;i++){
		if(p<=i){
			p = i+1;
			if(dq[i] == 'O')pref = 1;
			else pref = 0;
		}
		while(p<n&&pref<k){
			if(dq[p] == 'O')pref++;
			p++;
		}
		if(pref<k)op[i] = -1;
		else op[i] = p;
		if(dq[i] == 'O')pref--;
	}
	pref = 0;
	p = 0;
	for(int i = 0;i<n;i++){
		if(p<=i){
			p = i+1;
			if(dq[i] == 'I')pref = 1;
			else pref = 0;
		}
		while(p<n&&pref<k){
			if(dq[p] == 'I')pref++;
			p++;
		}
		if(pref<k)ip[i] = -1;
		else ip[i] = p;
		if(dq[i] == 'I')pref--;
	}
	for(int i = 0;i<n;i++){
		int r = i;
		r = jp[r];
		if(r == -1)continue;
		r = op[r];
		if(r == -1)continue;
		r = ip[r];
		if(r == -1)continue;
		ans = min(ans,r-i-k*3);
	}
	cout<<(ans == inf?-1:ans)<<'\n';
}

int main(){
	ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	int t=  1;
	while(t--)solve();
}

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