Submission #1079363

#	Time	Username	Problem	Language	Result	Execution time	Memory
1079363		alexander707070	Skyscraper (JOI16_skyscraper)	C++14	20 / 100	2054 ms	267600 KiB

skyscraper

#include<bits/stdc++.h>
#define MAXN 107
using namespace std;

const long long mod=1e9+7;

int n,s,a[MAXN],ans,pref[MAXN];

unordered_map<int,int> dp[MAXN][MAXN][3][3];

bool ok(int sum){
    return true;
   // return sum>=-5000 and sum<=s;
}

long long even(int pos,int bal,int sum,int l,int r){
    if(bal<0 or bal>n or sum>s)return 0;
    if(sum+pref[pos-(bal-n/2)]-pref[pos-1]>s)return 0;

    long long free=2*(bal-n/2)+(-(l==1)-(r==1)) - (-(l==2)-(r==2));
    if(free<0)return 0;

    if(pos==n+1 and bal==n/2 and l+r==3 and free==0)return 1;
    else if(pos==n+1 and (bal==n/2-1 or bal==n/2+1) and l==r and l!=0 and free==0)return 1;
    else if(pos==n+1)return 0;

    if(free==0 and pos!=1)return 0;

    if(dp[pos][bal][l][r].find(sum)!=dp[pos][bal][l][r].end())return dp[pos][bal][l][r][sum];
    long long curr=0;

    curr+=even(pos+1,bal,sum,l,r)*free;

    if(l==0){
        curr+=even(pos+1,bal+1,sum-a[pos],1,r);
        curr+=even(pos+1,bal-1,sum+a[pos],2,r);
    }

    if(r==0){
        curr+=even(pos+1,bal+1,sum-a[pos],l,1);
        curr+=even(pos+1,bal-1,sum+a[pos],l,2);
    }

    long long mult=bal-n/2+1-(l==1)-(r==1);
    long long mult2=bal-n/2-1+(l==2)+(r==2);

    curr+=even(pos+1,bal+1,sum-2*a[pos],l,r)*mult;
    curr+=even(pos+1,bal-1,sum+2*a[pos],l,r)*mult2;

    curr%=mod;
    dp[pos][bal][l][r][sum]=curr;

    return curr;
}

void calc_even(){
    ans+=even(1,n/2,0,0,0);
}

int main(){

    cin>>n>>s;

    int mins=1000;

    if(n==1){
        cout<<1<<"\n";
        return 0;
    }

    for(int i=1;i<=n;i++){
        cin>>a[i];
    }
    sort(a+1,a+n+1);

    mins=a[1];

    for(int i=1;i<=n;i++){
        a[i]-=mins;

        pref[i]=pref[i-1]+a[i];
    }

    calc_even();

    cout<<ans%mod<<"\n";

    return 0;
}

• Subtask 1: 5 / 5
• Subtask 2: 15 / 15
• Subtask 3: 0 / 80