Submission #1104270

#	Time	Username	Problem	Language	Result	Execution time	Memory
1104270		zephyrion	JJOOII 2 (JOI20_ho_t2)	C++17	0 / 100	1 ms	336 KiB

ho_t2

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

signed main() {
    int n, k;
    cin >> n >> k;
    string s1;
    cin >> s1;

    string s2 = "";
    for (int i = 0; i < k; i++){
        s2 += 'J';
    }
    for (int i = 0; i < k; i++){
        s2 += 'O';
    }
    for (int i = 0; i < k; i++){
        s2 += 'I';
    }
    vector<int> prefix_j(n + 1, 0), prefix_o(n + 1, 0), prefix_i(n + 1, 0);
    for (int i = 0; i < n; i++) {
        prefix_j[i+1] = prefix_j[i] + (s1[i] == 'J');
        prefix_o[i+1] = prefix_o[i] + (s1[i] == 'O');
        prefix_i[i+1] = prefix_i[i] + (s1[i] == 'I');
    }

    int ans = INT_MAX;

    for (int i = 0; i <= n - 3*k; i++) {
        if (s1[i] != 'J'){
            continue;
        }
        else{
            bool valid = true;
            for (int j = 0; j < k; j++) {
                if (s1[i + k + j] != 'O' || s1[i + 2 * k + j] != 'I') {
                    valid = false;
                    break;
                }
            }
            if (!valid){
                continue;
            }
            else{
                int tmp = 0;
                
                int j_start = i;
                int j_end = i + k;
                int j_count = prefix_j[j_end] - prefix_j[j_start];
                tmp += k - j_count; 
        
                int o_start = i + k;
                int o_end = i + 2 * k;
                int o_count = prefix_o[o_end] - prefix_o[o_start];
                tmp += k - o_count;
        
                int i_start = i + 2 * k;
                int i_end = i + 3 * k;
                int i_count = prefix_i[i_end] - prefix_i[i_start];
                tmp += k - i_count;
                
                ans = min(ans, tmp);
            }

        }
    }

    if (ans == INT_MAX) {
        cout << -1 << endl;
    } else {
        cout << ans << endl;
    }

    return 0;
}

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