Submission #868839

#	Time	Username	Problem	Language	Result	Execution time	Memory
868839		mzh	JJOOII 2 (JOI20_ho_t2)	C++17	100 / 100	29 ms	43240 KiB

ho_t2

#include <bits/stdc++.h>

using namespace std;

const int MXN = 2e5 + 5, LG = __lg(MXN) + 1;

int jmp[3][LG][MXN];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n, m;
    string s;
    cin >> n >> m >> s;

    for (int i = 0; i < 3; i++) {
        for (int j = 0; j < LG; j++) {
            for (int k = 0; k <= n + 1; k++) {
                jmp[i][j][k] = n + 1;
            }
        }
    }

    for (int i = 0; i < 3; i++) {
        for (int j = n - 1; j >= 0; j--) {
            jmp[i][0][j] = (s[j] == "JOI"[i] ? j + 1 : jmp[i][0][j + 1]);
        }
        for (int j = 1; j < LG; j++) {
            for (int k = 0; k + (1 << j) <= n; k++) {
                jmp[i][j][k] = jmp[i][j - 1][jmp[i][j - 1][k]];
            }
        }
    }

    int ans = 1e9;
    for (int i = 0; i < n; i++) {
        int idx = i;
        for (int j = 0; j < 3; j++) {
            for (int k = 0; k < LG; k++) {
                if ((m >> k) & 1) {
                    idx = jmp[j][k][idx];
                }
            }
        }
        if (idx != n + 1) {
            ans = min(ans, idx - i - 3 * m);
        }
    }
    cout << (ans == 1e9 ? -1 : ans) << '\n';
}

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