Submission #761956

#	Time	Username	Problem	Language	Result	Execution time	Memory
761956		dxz05	Linear Garden (IOI08_linear_garden)	C++17	100 / 100	437 ms	1428 KiB

linear_garden

//#pragma GCC optimize("Ofast,O3,unroll-loops")
//#pragma GCC target("avx2")

#include <bits/stdc++.h>

using namespace std;

#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define bpc(x) __builtin_popcount(x)
#define bpcll(x) __builtin_popcountll(x)
#define MP make_pair
//#define endl '\n'

mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());

typedef long long ll;
const int N = 1e6 + 3e2;

template<int D, typename T>
struct Vec : public vector<Vec<D - 1, T>> {
    static_assert(D >= 1, "Vector dimension must be greater than zero!");
    template<typename... Args>
    Vec(int n = 0, Args... args) : vector<Vec<D - 1, T>>(n, Vec<D - 1, T>(args...)) {
    }
};
template<typename T>
struct Vec<1, T> : public vector<T> {
    Vec(int n = 0, const T& val = T()) : vector<T>(n, val) {
    }
};

void solve(){
    int n, MOD; string s;
    cin >> n >> MOD >> s;

    vector dp(2, vector(3, vector(3, vector<int>(5, 0))));
    auto ndp = dp;

    function<int(int, int, int, int)> calc = [&](int small, int mx, int mn, int bal){
        mx = max(mx, bal);
        mn = min(mn, bal);
        if (mx > 2 || bal < -2 || bal > 2 || mn < -2) return 0;
        return dp[small][mx][2 + mn][2 + bal];
    };

    for (int i = n; i >= 1; i--){
        for (int small = 0; small <= 1; small++){
            for (int mx = 0; mx <= 2; mx++){
                for (int mn = -2; mn <= 0; mn++){
                    for (int bal = mn; bal <= mx; bal++){
                        int &res = ndp[small][mx][2 + mn][2 + bal];
                        res = 0;

                        if (mx - mn > 2) continue;
                        if (i == n){
                            res = 1;
                            continue;
                        }

                        if (small){
                            res += calc(1, mx, mn, bal - 1);
                            res += calc(1, mx, mn, bal + 1);
                        } else {
                            if (s[i] == 'L'){
                                res += calc(0, mx, mn, bal - 1);
                            } else {
                                res += calc(1, mx, mn, bal - 1);
                                res += calc(0, mx, mn, bal + 1);
                            }
                        }

                        res %= MOD;
                    }
                }
            }
        }

        swap(dp, ndp);
    }

    int res = 0;

    if (s[0] == 'L'){
        res += calc(0, 0, -1, -1);
    } else {
        res += calc(1, 0, -1, -1);
        res += calc(0, 1, 0, 1);
    }

    res %= MOD;

    cout << res << endl;

}

int main(){
    clock_t startTime = clock();
    ios_base::sync_with_stdio(false);

#ifdef LOCAL
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif

    int test_cases = 1;
//    cin >> test_cases;

    for (int test = 1; test <= test_cases; test++){
        // cout << (solve() ? "YES" : "NO") << endl;
        solve();
    }

#ifdef LOCAL
    cerr << "Time: " << int((double) (clock() - startTime) / CLOCKS_PER_SEC * 1000) << " ms" << endl;
#endif

    return 0;
}

Compilation message (stderr)

linear_garden.cpp: In function 'int main()':
linear_garden.cpp:98:13: warning: unused variable 'startTime' [-Wunused-variable]
   98 |     clock_t startTime = clock();
      |             ^~~~~~~~~

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