Submission #886964

#	Time	Username	Problem	Language	Result	Execution time	Memory
886964		Alora	Magneti (COCI21_magneti)	C++17	110 / 110	59 ms	13172 KiB

Main

#include <bits/stdc++.h>
#define Alora "cownav"
#define fi(i,a,b) for(int i = a; i <= b; i++)
#define fid(i,a,b) for(int i = a; i >= b; i--)
#define ll long long
#define f first
#define se second
#define pii pair<int, int>
#define getbit(i, j) ((i >> j) & 1)
#define all(v) v.begin(), v.end()
#define pb push_back
#define maxn 10088
const int M = 1e9 + 7;
using namespace std;
int n, l, r[55];
ll res, C[55][maxn], gt[55], dp[2][55][maxn];
void add(ll &x, ll y){x = (x + y) % M;}
ll mul(ll x, ll y) {return x*y % M;}

void pre(){
    fi(i, 1, l + n) C[0][i] = 1;
    C[1][1] = 1;
    fi(i, 2, l + n){
        fi(j, 1, min(50, i)){
            add(C[j][i], C[j][i - 1] + C[j - 1][i - 1]);
        }
    }
    gt[0] = 1;
    fi(i, 1, n) gt[i] = 1ll*gt[i - 1]*i % M;
}

void sub1(){
    if(n == 1) {cout << l; exit(0);}
    int len = l - (1 + r[1]*(n - 1));
    if(len < 0){cout << 0; exit(0);}
    len += n;
    cout << C[n][len]*gt[n] % M;
    exit(0);
}

int main(){
	ios_base::sync_with_stdio(0);
	cin.tie(NULL);
	if(fopen(Alora".inp", "r")){
    freopen(Alora".inp", "r", stdin);
    freopen(Alora".out", "w", stdout);}
    cin >> n >> l;
    pre();
    fi(i, 1, n) cin >> r[i];
    sort(r + 1, r + n + 1);
    if(r[1] == r[n]) sub1();
    dp[0][0][0] = 1;
    fi(i, 0, n - 1){
        fi(j, 0, i){
            fi(d, 0, l) if(dp[0][j][d]){
                ll x = dp[0][j][d];
                add(dp[1][j + 1][d + 1], mul(x, j + 1));
                if(d + r[i + 1] <= l) add(dp[1][j][d + r[i + 1]], mul(x, 2*j));
                if(j && d + 2*r[i + 1] - 1 <= l) add(dp[1][j - 1][d + 2*r[i + 1] - 1], mul(x, j - 1));
            }
        }
        swap(dp[0], dp[1]);
        fi(j, 0, i) fi(d, 0, l) dp[1][j][d] = 0;
    }
    fi(d, 1, l) add(res, mul(dp[0][1][d], C[n][l - d + n]));
    cout << res;
    return 0;
}

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:45:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   45 |     freopen(Alora".inp", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:46:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   46 |     freopen(Alora".out", "w", stdout);}
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

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