Submission #877885

#	Time	Username	Problem	Language	Result	Execution time	Memory
877885		alexdd	Bootfall (IZhO17_bootfall)	C++17	28 / 100	1035 ms	29272 KiB

bootfall

#include<iostream>
#include<bitset>
using namespace std;
int n,tot;
int a[505];
bitset<500005> pref[505];
bitset<500005> suff[505];
int variante[250005],cntv;
int newv[250005],cntnew;
int sump[505];
signed main()
{
    ios_base::sync_with_stdio(0);cin.tie(0);
    cin>>n;
    for(int i=1;i<=n;i++)
    {
        cin>>a[i];
        tot+=a[i];
        sump[i]=sump[i-1]+a[i];
    }
    pref[0][250000]=1;
    for(int i=1;i<=n;i++)
        pref[i] = ((pref[i-1]<<a[i]) | (pref[i-1]>>a[i]));
    suff[n+1][250000]=1;
    for(int i=n;i>0;i--)
        suff[i] = ((suff[i+1]<<a[i]) | (suff[i+1]>>a[i]));
    if(pref[n][250000]==0)
    {
        cout<<0;
        return 0;
    }
    for(int i=1;i<=tot;i++)
        variante[++cntv]=i;
    for(int i=1;i<=n;i++)
    {
        cntnew=0;
        for(int j=1;j<=cntv;j++)
        {
            int x = variante[j];
            for(int difs=-sump[i-1];difs<=sump[i-1];difs++)
            {
                ///difs + difd + x = 0  =>  difd = -difs - x
                ///difs + difd - x = 0  =>  difd = -difs + x
                if((-tot<=-difs-x && -difs-x<=tot && pref[i-1][difs+250000] && suff[i+1][-difs-x+250000]) || (-tot<=-difs+x && -difs+x<=tot && pref[i-1][difs+250000] && suff[i+1][-difs+x+250000]))
                {
                    newv[++cntnew] = variante[j];
                    break;
                }
            }
        }
        cntv = cntnew;
        for(int j=1;j<=cntnew;j++)
            variante[j] = newv[j];
    }
    cout<<cntv<<"\n";
    for(int i=1;i<=cntv;i++)
        cout<<variante[i]<<" ";
    return 0;
}
/**

difs + difd +- x = 0  =>  x = abs(difs + difd)
x = difs + difd
    sau
x = -difs - difd

4
1 3 1 5

6
3 5 7 11 9 13

*/

• Subtask 1: 6 / 6
• Subtask 2: 7 / 7
• Subtask 3: 15 / 15
• Subtask 4: 0 / 16
• Subtask 5: 0 / 21
• Subtask 6: 0 / 35