Submission #886960

#	Time	Username	Problem	Language	Result	Execution time	Memory
886960		Alora	Magneti (COCI21_magneti)	C++17	110 / 110	93 ms	12688 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;
    int t = 0;
    fi(i, 1, n){
        t ^= 1;
        dp[t][0][0] = 0;
        fi(j, 1, i){
            fi(d, 1, l){
                dp[t][j][d] = dp[1 - t][j - 1][d - 1]; // add new
                if(d >= r[i]) add(dp[t][j][d], mul(dp[1 - t][j][d - r[i]], 2*j)); // add
                if(d >= 2*r[i] - 1) add(dp[t][j][d], mul(dp[1 - t][j + 1][d - 2*r[i] + 1], (j + 1)*j)); // connect
            }
        }
    }
    fi(d, 1, l) add(res, mul(dp[t][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