# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
1232355 | hainam2k9 | Magneti (COCI21_magneti) | C++20 | 21 ms | 5696 KiB |
#include <bits/stdc++.h>
#define tt cin.tie(0), cout.tie(0), ios_base::sync_with_stdio(0)
#define fo freopen((NAME+".INP").c_str(), "r", stdin), freopen((NAME+".OUT").c_str(), "w", stdout)
#define ll long long
#define ull unsigned long long
#define i128 __int128
#define db long double
#define sz(a) ((int)(a).size())
#define pb emplace_back
#define pf emplace_front
#define pob pop_back
#define pof pop_front
#define lb lower_bound
#define ub upper_bound
#define fi first
#define se second
#define ins emplace
#define mp make_pair
using namespace std;
const int MOD = 1e9+7, MAXN = 1e4+5;
const string NAME = "";
int n,l,a[55],dp[55][55][MAXN],rs=0;
void add(int& a, int b){
a+=b;
if(a>=MOD) a-=MOD;
}
int modpow(int a, int b){
if(b==0) return 1;
ll half=modpow(a,b>>1);
half=(half*half)%MOD;
if(b&1) return (half*a)%MOD;
return half;
}
int main()
{
tt;
if(fopen((NAME + ".INP").c_str(), "r")) fo;
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){
if(dp[i][j][k]==0) continue;
add(dp[i+1][j+1][k],1ll*(j+1)*dp[i][j][k]%MOD);
if(j>=1&&k+a[i+1]<l) add(dp[i+1][j][k+a[i+1]],2ll*j*dp[i][j][k]%MOD);
if(j>=2&&k+2*a[i+1]<l) add(dp[i+1][j-1][k+2*a[i+1]],dp[i][j][k]);
}
for(int i = 0; i<l; ++i)
add(rs,1ll*dp[n][1][i]*modpow(l-i,n)%MOD);
cout << rs;
}
Compilation message (stderr)
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