Submission #1258872

#	Time	Username	Problem	Language	Result	Execution time	Memory
1258872		trandangquang	Skyscraper (JOI16_skyscraper)	C++20	100 / 100	25 ms	15940 KiB

skyscraper

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

#pragma GCC optimize("O3")
#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 all(a) (a).begin(),(a).end()
#define sz(a) (int)(a).size()
#define ii pair<int,int>
#define fi first
#define se second
#define eb emplace_back
#define pb push_back
#define ll long long

const int N=105;
const int mod=1e9+7;

int n,l,a[N],dp[N][N][1001][3];

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;
}

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

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

    sort(a+1,a+1+n);

    dp[0][0][0][0]=1;
    foru(i,0,n-1) foru(cc,0,i) foru(cost,0,l) foru(fe,0,2){
        int ncost=(2*cc-fe)*(a[i+1]-a[i]), r=dp[i][cc][cost][fe];

        if(cost+ncost>l || r==0) continue;

        ///t1
        add(dp[i+1][cc+1][cost+ncost][fe], mul(r,cc+1-fe));
        if(fe<2) add(dp[i+1][cc+1][cost+ncost][fe+1], mul(r,2-fe));

        ///t2
        if(cc>=1){
            add(dp[i+1][cc][cost+ncost][fe], mul(r,2*cc-fe));
            if(fe<2) add(dp[i+1][cc][cost+ncost][fe+1], mul(r,2-fe));
        }

        ///t3
        if(cc>=2){
            add(dp[i+1][cc-1][cost+ncost][fe], mul(r,cc-1));
        }
    }

    int res=0;
    foru(lp,0,l){
        add(res,dp[n][1][lp][2]);
    }
    cout<<res<<'\n';
}

int 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);

//    double start=clock();
    solve();
//    fprintf(stderr, "Elapsed time: %.3fs\n", (clock()-start)/CLOCKS_PER_SEC);
}

Compilation message (stderr)

skyscraper.cpp: In function 'int main()':
skyscraper.cpp:72:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   72 |         freopen(task".inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
skyscraper.cpp:73:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   73 |         freopen(task".out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 15 / 15
• Subtask 3: 80 / 80