Submission #975351

#	Time	Username	Problem	Language	Result	Execution time	Memory
975351		12345678	Bootfall (IZhO17_bootfall)	C++17	100 / 100	554 ms	17228 KiB

bootfall

#include <bits/stdc++.h>

using namespace std;

#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")

const int nx=505, kx=250005;

int n, a[nx], sm;
bitset<kx> dp[nx], l, r;
vector<int> res;

bool valid(int x)
{
    for (int i=1; i<=n; i++) if (((sm-a[i]+x)%2)||(!dp[i][(sm-a[i]+x)/2])) return 0;
    return 1;
}
int main()
{
    cin.tie(NULL)->sync_with_stdio(false);
    cin>>n;
    for (int i=1; i<=n; i++) cin>>a[i], sm+=a[i];
    for (int i=0; i<=n; i++) dp[i][0]=1;
    l[0]=r[0]=1;
    for (int i=1; i<=n; i++)
    {
        if (i>=n/2) dp[i]=l;
        l=l|(l<<a[i]);
    }
    dp[0]=l;
    for (int i=n; i>=1; i--)
    {
        if (i<n/2) dp[i]=r;
        r=r|(r<<a[i]);
    }
    for (int i=1; i<=n; i++)
    {
        if (i>=n/2) for (int j=i+1; j<=n; j++) dp[i]=dp[i]|(dp[i]<<a[j]);
        else for (int j=1; j<i; j++) dp[i]=dp[i]|(dp[i]<<a[j]);
    }
    if ((sm%2)||!dp[0][sm/2]) return cout<<0, 0;
    for (int i=1; i<kx; i++) if (valid(i)) res.push_back(i);
    cout<<res.size()<<'\n';
    for (auto x:res) cout<<x<<' ';
}

/*
4
1 3 1 5
*/

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