Submission #1266672

#	Time	Username	Problem	Language	Result	Execution time	Memory
1266672		SnowRaven52	Linear Garden (IOI08_linear_garden)	C++20	100 / 100	29 ms	24804 KiB

linear_garden

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

int main() {
  // freopen("main.in", "r", stdin);
	// freopen(".out", "w", stdout);
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int N; int M; cin >> N >> M;
    string S; cin >> S;

    auto nxt = [&](int st, char ch)->int {
        switch (st) {
            case 0: return (ch=='L'? 2 : 1);
            case 1: return (ch=='L'? 2 : 3);
            case 2: return (ch=='L'? 5 : 1);
            case 3: return (ch=='L'? 4 : -1);
            case 4: return (ch=='L'? 5 : 3);
            case 5: return (ch=='L'? -1 : 4);
        }
        return -1;
    };

    vector<array<int,6>> dp(N+1);
    for (int s = 0; s < 6; s++) dp[0][s] = 1 % M;
    for (int len = 1; len <= N; len++) {
        for (int s = 0; s < 6; s++) {
            long long v = 0;
            int a = nxt(s, 'L'); if (a != -1) v += dp[len-1][a];
            int b = nxt(s, 'P'); if (b != -1) v += dp[len-1][b];
            dp[len][s] = int(v % M);
        }
    }

    long long ans = 1 % M;
    int st = 0;
    for (int i = 0; i < N; i++) {
        int rem = N - i;
        if (S[i] == 'P') {
            int a = nxt(st, 'L');
            if (a != -1) ans = (ans + dp[rem-1][a]) % M;
            st = nxt(st, 'P');
        } else {
            st = nxt(st, 'L');
        }
    }
    cout << (ans % M) << endl;
}

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• Subtask 2: 2 / 2
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• Subtask 23: 5 / 5