Submission #1267277

#	Time	Username	Problem	Language	Result	Execution time	Memory
1267277		baotoan655	Magneti (COCI21_magneti)	C++20	110 / 110	97 ms	58252 KiB

Main

#include <bits/stdc++.h>
#define file(name)  if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
using namespace std;

const int MOD = 1e9 + 7;
inline int add(int x, int y) {
    x += y;
    if(x >= MOD) x -= MOD;
    return x;
}
inline int mul(int x, int y) {
    return (long long) x * y % MOD;
}
int exp(int a, int b) {
    int res = 1;
    while(b > 0) {
        if(b & 1) res = mul(res, a);
        a = mul(a, a);
        b >>= 1;
    }
    return res;
}
const int N = 2e4 + 5;
int a[55];
int dp[55][55][N], f[N], inv[N];

int C(int n, int k) {
    return mul(f[n], mul(inv[k], inv[n - k]));
}
int n,l;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);

    file("A") else file("task");

    f[0] = 1;
    for(int i = 1; i < N; ++i) f[i] = mul(f[i - 1], i);
    inv[N - 1] = exp(f[N - 1], MOD - 2);
    for(int i = N - 2; i >= 0; --i) {
        inv[i] = mul(inv[i + 1], i + 1);
    }

    cin >> n >> l;
    for(int i = 1; i <= n; ++i) cin >> a[i];
    sort(a + 1, a + n + 1);
    
    dp[0][0][0] = 1;
    for(int i = 0; i < n; ++i) {
        for(int j = 0; j <= i; ++j) {
            for(int k = 0; k < l; ++k) {
                dp[i + 1][j + 1][k + 1] = add(dp[i + 1][j + 1][k + 1], mul(j + 1, dp[i][j][k]));
                if(k + a[i + 1] <= l) dp[i + 1][j][k + a[i + 1]] = add(dp[i + 1][j][k + a[i + 1]], mul(2 * j, dp[i][j][k]));
                if(j > 0 && k + 2 * a[i + 1] - 1 <= l) dp[i + 1][j - 1][k + 2 * a[i + 1] - 1] = add(dp[i + 1][j - 1][k + 2 * a[i + 1] - 1], mul(j - 1, dp[i][j][k]));
            }
        }
    }
    int ans = 0;
    for(int i = 1; i <= l; ++i) {
        ans = add(ans, mul(dp[n][1][i], C(l - i + n, n)));
    }
    cout << ans << '\n';

}

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:2:58: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    2 | #define file(name)  if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
      |                                                   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:36:5: note: in expansion of macro 'file'
   36 |     file("A") else file("task");
      |     ^~~~
Main.cpp:2:91: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    2 | #define file(name)  if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
      |                                                                                    ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:36:5: note: in expansion of macro 'file'
   36 |     file("A") else file("task");
      |     ^~~~
Main.cpp:2:58: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    2 | #define file(name)  if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
      |                                                   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:36:20: note: in expansion of macro 'file'
   36 |     file("A") else file("task");
      |                    ^~~~
Main.cpp:2:91: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    2 | #define file(name)  if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
      |                                                                                    ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:36:20: note: in expansion of macro 'file'
   36 |     file("A") else file("task");
      |                    ^~~~

• Subtask 1: 10 / 10
• Subtask 2: 20 / 20
• Subtask 3: 30 / 30
• Subtask 4: 50 / 50