Submission #1188050

#	Time	Username	Problem	Language	Result	Execution time	Memory
1188050		MisterReaper	Skyscraper (JOI16_skyscraper)	C++20	100 / 100	129 ms	130604 KiB

skyscraper

// File A.cpp created on 18.04.2025 at 16:38:14
#include <bits/stdc++.h>

using i64 = long long;

#ifdef DEBUG 
    #include "/home/ahmetalp/Desktop/Workplace/debug.h"
#else
    #define debug(...) void(23)
#endif

template<typename T>
T power(T a, i64 b) {
    T res{1};
    while (b) {
        if (b & 1) {
            res *= a;
        }
        a *= a;
        b >>= 1;
    }
    return res;
}

constexpr int md = int(1E9) + 7;
struct MInt {
    int val;
    MInt() : val(0) {}
    template<typename T>
    MInt(T x) {
        if (-md <= x && x < md) {
            val = x;
        } else {
            val = x % md;
        }
    }
    int operator()() { return val; }
    MInt& operator+= (MInt rhs) {
        if ((val += rhs.val) >= md) {
            val -= md;
        }
        return *this;
    }
    MInt& operator-= (MInt rhs) {
        if ((val -= rhs.val) < 0) {
            val += md;
        }
        return *this;
    }
    MInt& operator*= (MInt rhs) {
        val = (1LL * val * rhs.val) % md;
        return *this;
    }
    MInt inv() {
        return power(*this, md - 2);
    }
    MInt& operator/= (MInt rhs) {
        return *this *= rhs.inv();
    }
    bool operator== (MInt rhs) {
        return val == rhs.val;
    }
};
MInt operator+ (MInt lhs, MInt rhs) {
    return lhs += rhs;
}
MInt operator- (MInt lhs, MInt rhs) {
    return lhs -= rhs;
}
MInt operator* (MInt lhs, MInt rhs) {
    return lhs *= rhs;
}
MInt operator/ (MInt lhs, MInt rhs) {
    return lhs /= rhs;
}
std::ostream& operator<< (std::ostream& os, MInt x) {
    return os << x.val;
}

using Z = MInt;

constexpr int max_N = int(100) + 5;
constexpr int max_L = int(1000) + 5;

int A[max_N];
Z f[max_N][max_N][max_L][3];
// std::vector f(max_N, std::vector(max_N, std::vector(max_L, std::vector<Z>(3))));

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

    int N, L;
    std::cin >> N >> L;
    for (int i = 1; i <= N; ++i) {
        std::cin >> A[i];
    }

    if (N == 1) {
        std::cout << "1\n";
        return 0;
    }

    std::sort(A + 1, A + N + 1);

    f[0][0][0][0] = 1;
    A[N + 1] = 2 * L;

    for (int i = 1; i <= N; ++i) {
        for (int j = 1; j <= N; ++j) {
            for (int m = 0; m < 3; ++m) {
                int delta = (2 * j - m) * (A[i + 1] - A[i]);
                for (int k = delta; k <= L; ++k) {
                    // Case 1: Insert new component without border
                    f[i][j][k][m] += f[i - 1][j - 1][k - delta][m];
                    // Case 2: Insert new component with border
                    if (m > 0) {
                        f[i][j][k][m] += (3 - m) * f[i - 1][j - 1][k - delta][m - 1];
                    }
                    // Case 3: Insert an edge of a component and not border
                    f[i][j][k][m] += (2 * j - m) * f[i - 1][j][k - delta][m];
                    // Case 4: Insert an edge of a component and do border
                    if (m > 0) {
                        if (m == 1) {
                            f[i][j][k][m] += 2 * j * f[i - 1][j][k - delta][m - 1];
                        } else {
                            if (i == N) {
                                f[i][j][k][m] += f[i - 1][j][k - delta][m - 1];
                            } else if (j > 1) {
                                f[i][j][k][m] += (j - 1) * f[i - 1][j][k - delta][m - 1];
                            }
                        }
                    }
                    // Case 5: Merge two components
                    if (m == 2) {
                        if (i == N) {
                            f[i][j][k][m] += f[i - 1][j + 1][k - delta][m];
                        } else {
                            f[i][j][k][m] += j * (j - 1) * f[i - 1][j + 1][k - delta][m];
                        }
                    } else if (m == 1) {
                        f[i][j][k][m] += j * j * f[i - 1][j + 1][k - delta][m];
                    } else {
                        f[i][j][k][m] += j * (j + 1) * f[i - 1][j + 1][k - delta][m];
                    }
                }
            }
        }
    }

    Z ans = 0;
    for (int i = 0; i <= L; ++i) {
        ans += f[N][1][i][2];
    }

    std::cout << ans << '\n';

    return 0;
}

• Subtask 1: 5 / 5
• Subtask 2: 15 / 15
• Subtask 3: 80 / 80