Submission #1053685

#	Time	Username	Problem	Language	Result	Execution time	Memory
1053685		dpsaveslives	JJOOII 2 (JOI20_ho_t2)	C++17	100 / 100	11 ms	5452 KiB

ho_t2

#include <bits/stdc++.h>
using namespace std;
const int MAXN = 2e5+5;
int pref[3][MAXN],dp[3][MAXN];
int main(){
    int N,K; cin >> N >> K;
    for(int i = 1;i<=N;++i){
        char c; cin >> c;
        if(c == 'J') pref[0][i]++;
        else if(c == 'O') pref[1][i]++;
        else pref[2][i]++;
        pref[0][i] += pref[0][i-1];
        pref[1][i] += pref[1][i-1];
        pref[2][i] += pref[2][i-1];
    }
    memset(dp[0],0x3f,sizeof(dp[0]));
    int cur = 1e9, pos = 0;
    for(int i = 1;i<=N;++i){
        while(pref[0][i]-pref[0][pos] >= K && pos < i){
            cur = min(cur,-pos);
            pos++;
        }
        dp[0][i] = cur+i;
    }
    memset(dp[1],0x3f,sizeof(dp[1]));
    cur = 1e9; pos = 0;
    for(int i = 1;i<=N;++i){
        while(pref[1][i]-pref[1][pos] >= K && pos < i){
            cur = min(cur,dp[0][pos]-pos);
            pos++;
        }
        dp[1][i] = cur+i;
    }
    memset(dp[2],0x3f,sizeof(dp[2]));
    cur = 1e9; pos = 0;
    for(int i = 1;i<=N;++i){
        while(pref[2][i]-pref[2][pos] >= K && pos < i){
            cur = min(cur,dp[1][pos]-pos);
            pos++;
        }
        dp[2][i] = cur+i;
    }
    int ans = *min_element(dp[2],dp[2]+N+1) - 3*K;
    if(ans > 1e7) cout << -1 << "\n";
    else cout << ans << "\n";
    return 0;
}

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