Submission #474687

#	Time	Username	Problem	Language	Result	Execution time	Memory
474687		vincent97198	JJOOII 2 (JOI20_ho_t2)	C++14	100 / 100	9 ms	3028 KiB

ho_t2

#include <bits/stdc++.h>

using namespace std;

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);   cout.tie(nullptr);
    
    int n,k;    cin >> n >> k;
    string s;   cin >> s;
    vector<int> pos(n),near_O(n),near_I(n);
    int J_r=-1,J_cnt=0,O_r=-1,O_cnt=0,I_r=-1,I_cnt=0;
    for(int i=0;i<n;++i){
        while(J_cnt<k && J_r<n){
            ++J_r;
            if(s[J_r]=='J') ++J_cnt;
        }
        while(O_cnt<k && O_r<n){
            ++O_r;
            if(s[O_r]=='O') ++O_cnt;
        }
        while(I_cnt<k && I_r<n){
            ++I_r;
            if(s[I_r]=='I') ++I_cnt;
        }
        
        if(s[i]=='J'){
            if(J_cnt==k)    pos[i]=J_r;
            else pos[i]=-1;
            --J_cnt;
        }
        else if(s[i]=='O'){
            if(O_cnt==k)    pos[i]=O_r;
            else pos[i]=-1;
            --O_cnt;
        }
        else{
            if(I_cnt==k)    pos[i]=I_r;
            else pos[i]=-1;
            --I_cnt;
        }
    }
    
    int O_is_here=-1,I_is_here=-1;
    for(int i=n-1;i>=0;--i){
        if(s[i]=='O')   O_is_here=i;
        near_O[i]=O_is_here;
    }
    for(int i=n-1;i>=0;--i){
        if(s[i]=='I')   I_is_here=i;
        near_I[i]=I_is_here;
    }
    
    // for(int i=0;i<n;++i)    cout << "pos" << i << ": " << pos[i] << endl;
    
    int ans=(1<<30);
    for(int i=0;i<n;++i){
        int tmp=0;
        if(s[i]=='J'){
            if(pos[i]==-1)  continue;
            tmp+=pos[i]-i+1-k;
            if(near_O[pos[i]]==-1 || pos[near_O[pos[i]]]==-1)  continue;
            tmp+=pos[near_O[pos[i]]]-near_O[pos[i]]+1-k+near_O[pos[i]]-pos[i]-1;
            if(near_I[pos[near_O[pos[i]]]]==-1 || pos[near_I[pos[near_O[pos[i]]]]]==-1) continue;
            tmp+=pos[near_I[pos[near_O[pos[i]]]]]-near_I[pos[near_O[pos[i]]]]+1-k+near_I[pos[near_O[pos[i]]]]-pos[near_O[pos[i]]]-1;
            /*
            cout << i << " " << near_O[pos[i]] << " " << near_I[pos[near_O[pos[i]]]] << endl;
            cout << "ww\n";
            cout << pos[i] << " " << pos[near_O[pos[i]]] << " " << pos[near_I[pos[near_O[pos[i]]]]] << endl;
            */
            ans=min(ans,tmp);
        }
        
    }
    if(ans!=(1<<30))    cout << ans << '\n';
    else    cout << -1 << '\n';
    
    return 0;
}

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