oj.uz

Submission #521487

# Submission time Handle Problem Language Result Execution time Memory
521487 2022-02-02T08:53:59 Z tengiz05 Skyscraper (JOI16_skyscraper) C++17
100 / 100
 329 ms 2892 KB 
#include <bits/stdc++.h>

constexpr int P = 1E9 + 7;
using i64 = long long;
// assume -P <= x < 2P
int norm(int x) {
    if (x < 0) {
        x += P;
    }
    if (x >= P) {
        x -= P;
    }
    return x;
}
template<class T>
T power(T a, int b) {
    T res = 1;
    for (; b; b /= 2, a *= a) {
        if (b % 2) {
            res *= a;
        }
    }
    return res;
}
struct Z {
    int x;
    Z(int x = 0) : x(norm(x)) {}
    int val() const {
        return x;
    }
    Z operator-() const {
        return Z(norm(P - x));
    }
    Z inv() const {
        assert(x != 0);
        return power(*this, P - 2);
    }
    Z &operator*=(const Z &rhs) {
        x = i64(x) * rhs.x % P;
        return *this;
    }
    Z &operator+=(const Z &rhs) {
        x = norm(x + rhs.x);
        return *this;
    }
    Z &operator-=(const Z &rhs) {
        x = norm(x - rhs.x);
        return *this;
    }
    Z &operator/=(const Z &rhs) {
        return *this *= rhs.inv();
    }
    friend Z operator*(const Z &lhs, const Z &rhs) {
        Z res = lhs;
        res *= rhs;
        return res;
    }
    friend Z operator+(const Z &lhs, const Z &rhs) {
        Z res = lhs;
        res += rhs;
        return res;
    }
    friend Z operator-(const Z &lhs, const Z &rhs) {
        Z res = lhs;
        res -= rhs;
        return res;
    }
    friend Z operator/(const Z &lhs, const Z &rhs) {
        Z res = lhs;
        res /= rhs;
        return res;
    }
};

constexpr int N = 1005;
Z dp[2][105][3][N + 1];

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    
    int n, L;
    std::cin >> n >> L;
    
    std::vector<int> a(n);
    for (int i = 0; i < n; i++) {
        std::cin >> a[i];
    }
    std::sort(a.begin(), a.end());
    
    if (n == 1) {
        std::cout << 1 << "\n";
        return 0;
    }
    
    int cur = 0;
    dp[cur][0][0][0] = 1;
    for (int i = 0; i < n; i++) {
        int x = i == 0 ? 0 : a[i] - a[i - 1];
        cur ^= 1;
        std::memset(dp[cur], 0, sizeof dp[cur]);
        for (int c = 0; c < n; c++) {
            for (int j = 0; j <= N; j++) {
                if (j + 2 * c * x <= N) {
                    int to = j + 2 * c * x;
                    dp[cur][c + 1][0][to] += (c + 1) * dp[cur ^ 1][c][0][j];
                    dp[cur][c + 1][1][to] += 2 * dp[cur ^ 1][c][0][j];
                    if (c > 0) {
                        dp[cur][c][1][to] += 2 * dp[cur ^ 1][c][0][j];
                        dp[cur][c][0][to] += 2 * c * dp[cur ^ 1][c][0][j];
                    }
                    if (c > 1) {
                        dp[cur][c - 1][0][to] += (c - 1) * dp[cur ^ 1][c][0][j];
                    }
                }
                
                if (c > 0 && j + (2 * c - 1) * x <= N) {
                    int to = j + (2 * c - 1) * x;
                    dp[cur][c + 1][1][to] += c * dp[cur ^ 1][c][1][j];
                    dp[cur][c + 1][2][to] += dp[cur ^ 1][c][1][j];
                    if (c > 0) {
                        dp[cur][c][2][to] += dp[cur ^ 1][c][1][j];
                        dp[cur][c][1][to] += (2 * c - 1) * dp[cur ^ 1][c][1][j];
                    }
                    if (c > 1) {
                        dp[cur][c - 1][1][to] += (c - 1) * dp[cur ^ 1][c][1][j];
                    }
                }
                
                if (c > 1 && j + (2 * c - 2) * x <= N) {
                    int to = j + (2 * c - 2) * x;
                    dp[cur][c + 1][2][to] += (c - 1) * dp[cur ^ 1][c][2][j];
                    if (c > 0) {
                        dp[cur][c][2][to] += (2 * c - 2) * dp[cur ^ 1][c][2][j];
                    }
                    if (c > 1) {
                        dp[cur][c - 1][2][to] += (c - 1) * dp[cur ^ 1][c][2][j];
                    }
                }
            }
        }
    }
    
    std::cout << std::accumulate(dp[cur][1][2], dp[cur][1][2] + L + 1, Z(0)).val() << "\n";
    
    return 0;
}

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2796 KB Output is correct
2 Correct 2 ms 2764 KB Output is correct
3 Correct 2 ms 2796 KB Output is correct
4 Correct 2 ms 2764 KB Output is correct
5 Correct 2 ms 2796 KB Output is correct
6 Correct 3 ms 2764 KB Output is correct
7 Correct 3 ms 2800 KB Output is correct
8 Correct 4 ms 2764 KB Output is correct
9 Correct 3 ms 2764 KB Output is correct
10 Correct 4 ms 2764 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 2764 KB Output is correct
2 Correct 7 ms 2796 KB Output is correct
3 Correct 7 ms 2764 KB Output is correct
4 Correct 7 ms 2796 KB Output is correct
5 Correct 7 ms 2764 KB Output is correct
6 Correct 7 ms 2792 KB Output is correct
7 Correct 8 ms 2796 KB Output is correct
8 Correct 7 ms 2892 KB Output is correct
9 Correct 8 ms 2764 KB Output is correct
10 Correct 8 ms 2776 KB Output is correct

Subtask #3
80.0 / 80.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2796 KB Output is correct
2 Correct 2 ms 2764 KB Output is correct
3 Correct 2 ms 2796 KB Output is correct
4 Correct 2 ms 2764 KB Output is correct
5 Correct 2 ms 2796 KB Output is correct
6 Correct 3 ms 2764 KB Output is correct
7 Correct 3 ms 2800 KB Output is correct
8 Correct 4 ms 2764 KB Output is correct
9 Correct 3 ms 2764 KB Output is correct
10 Correct 4 ms 2764 KB Output is correct
11 Correct 8 ms 2764 KB Output is correct
12 Correct 7 ms 2796 KB Output is correct
13 Correct 7 ms 2764 KB Output is correct
14 Correct 7 ms 2796 KB Output is correct
15 Correct 7 ms 2764 KB Output is correct
16 Correct 7 ms 2792 KB Output is correct
17 Correct 8 ms 2796 KB Output is correct
18 Correct 7 ms 2892 KB Output is correct
19 Correct 8 ms 2764 KB Output is correct
20 Correct 8 ms 2776 KB Output is correct
21 Correct 51 ms 2764 KB Output is correct
22 Correct 167 ms 2776 KB Output is correct
23 Correct 155 ms 2764 KB Output is correct
24 Correct 197 ms 2764 KB Output is correct
25 Correct 146 ms 2780 KB Output is correct
26 Correct 161 ms 2884 KB Output is correct
27 Correct 329 ms 2780 KB Output is correct
28 Correct 293 ms 2772 KB Output is correct
29 Correct 251 ms 2784 KB Output is correct
30 Correct 144 ms 2764 KB Output is correct