Submission #927739

#	Time	Username	Problem	Language	Result	Execution time	Memory
927739		weakweakweak	JJOOII 2 (JOI20_ho_t2)	C++14	13 / 100	7 ms	4072 KiB

ho_t2

/*
5:05開始，也不算是virtual，因為我已經知道幾個人的分數了，也在去年資芽時聽過p4的題敘並想過。
所以就只是計時練習，應該會寫到19:05，然後等家長買晚餐回來吃後再把剩下的兩小時用一用，衝到div2就打div2
目標日本選訓!!
*/
//喔，就只是雙指針而已
#include <bits/stdc++.h>
using namespace std;

string s;
int n, k, a[310000] = {0};
int cnt[3] = {0}, wow[210000][3];

int main () {
    ios_base::sync_with_stdio(false); cin.tie(0);
    cin >> n >> k;
    cin >> s;
    for (int i = 1; i <= n; i++) {
        if (s[i-1] == 'J') a[i] = 0;
        if (s[i-1] == 'O') a[i] = 1;
        if (s[i-1] == 'I') a[i] = 2;
    }

    for (int z = 0; z < 3; z++) {
        for (int i = 1, j = 0, cnt = 0; i <= n; i++) {
            while (j + 1 <= n and cnt < k) {
                j++;
                if (a[j] == z) cnt++;
            }
            if (cnt == k) wow[i][z] = j + 1;
            else wow[i][z] = 209999;
            if (a[i] == z) cnt--;
        }
    }
    wow[n+1][0] = wow[n+1][1] = wow[209999][0] = wow[209999][1] = 209999, wow[n+1][2] = wow[209999][2] = n * 114;

    int ans = INT_MAX;
    for (int i = 1; i <= n; i++) {
        // cout << i << ' ' << wow[i][0] << ' ' << wow[i][1] << ' ' << wow[i][2] << '\n';
        // cout << i << ' ' << wow[wow[wow[i][0]][1]][2] << '\n';
        ans = min(ans,  wow[wow[wow[i][0]][1]][2]  - i - k * 3 );
    }

    if (ans > n) ans = -1;
    cout << ans << '\n';
}

• Subtask 1: 1 / 1
• Subtask 2: 12 / 12
• Subtask 3: 0 / 87