Submission #1259245

#	Time	Username	Problem	Language	Result	Execution time	Memory
1259245		trandangquang	Magneti (COCI21_magneti)	C++20	110 / 110	114 ms	28408 KiB

Main

#include <bits/stdc++.h>
using namespace std;

#define foru(i, a, b) for(int i = (a); i <= (b); ++i)
#define ford(i, a, b) for(int i = (a); i >= (b); --i)
#define rep(i, a) for(int i = 0; i < (a); ++i)
#define sz(a) (int)(a).size()
#define all(a) (a).begin(), (a).end()
#define bit(s, i) (((s) >> (i)) & 1)
#define ii pair <int, int>
#define fi first
#define se second
#define ll long long
#define eb emplace_back
#define pb push_back
#define __builtin_popcount __builtin_popcountll

template <class X, class Y>
    bool maxi(X &x, Y y) {
        if(x < y) {
            x = y;
            return true;
        }
        return false;
    }

template <class X, class Y>
    bool mini(X &x, Y y) {
        if(x > y) {
            x = y;
            return true;
        }
        return false;
    }

const int N=55;
const int L=10101;
const int mod=1e9+7;

int n,l,r[N],dp[N][N][L][3];
int f[L],invf[L];

inline void add(int &a, int b){
    a+=b; if(a>=mod) a-=mod;
}
inline int mul(int a, int b){
    return (ll)a*b % mod;
}
inline int pw(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;
}
inline int nCk(int n, int k){
    return mul(f[n], mul(invf[k], invf[n-k]));
}

void solve(){
    cin>>n>>l;
    foru(i,1,n) cin>>r[i];

    if(n==1){
        cout<<l<<'\n';
        return;
    }

    sort(r+1, r+1+n, greater<int>());
    dp[0][0][0][0]=1;
    foru(i,0,n-1) foru(cc,0,i) foru(len,0,l) foru(fe,0,2) if(dp[i][cc][len][fe]>0){
        int dpt=dp[i][cc][len][fe];

        if(len+1+(r[i+1]-1)*2<=l)
            add(dp[i+1][cc+1][len+1+(r[i+1]-1)*2][fe], mul(dpt,cc+1-fe));
        if(fe<2 && len+r[i+1]<=l)
            add(dp[i+1][cc+1][len+r[i+1]][fe+1], mul(dpt,2-fe));

        if(cc>=1){
            if(len+r[i+1]<=l)
                add(dp[i+1][cc][len+r[i+1]][fe], mul(dpt,2*cc-fe));
            if(fe<2 && len+1<=l)
                add(dp[i+1][cc][len+1][fe+1], mul(dpt,2-fe));
        }

        if(cc>1 && len+1<=l)
            add(dp[i+1][cc-1][len+1][fe], mul(dpt,cc-1));
    }

    f[0]=1;
    foru(i,1,L-1) f[i]=mul(f[i-1],i);
    invf[L-1]=pw(f[L-1], mod-2);
    ford(i,L-2,0) invf[i]=mul(invf[i+1],i+1);

    int res=0;
    foru(i,n,l){
        add(res, mul(dp[n][1][i][2], nCk(n+l-i,n)));
    }
    cout<<res<<'\n';
}

int32_t main() {
    #define task "test"
    if(fopen(task".inp", "r")){
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }
    cin.tie(0)->sync_with_stdio(0);

    int tc = 1; // cin >> tc;
    foru(i, 1, tc){
        solve();
    }
}

Compilation message (stderr)

Main.cpp: In function 'int32_t main()':
Main.cpp:107:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  107 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:108:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  108 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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