981D - Bookshelves - CodeForces Solution

#include<bits/stdc++.h>
#define ll long long
using namespace std;
int const N=515;
int n,k;
ll a[N],s[N];
set<ll>f[N][N];
int main(){
	scanf("%d%d",&n,&k);
	for(int i=1;i<=n;i++)
		scanf("%lld",&a[i]),f[i][1].insert(s[i]=s[i-1]+a[i]);
	for(int i=2;i<=k;i++)
		for(int l=1;l<=n;l++)
			for(int r=l;r<=n;r++)
				for(ll x:f[l-1][i-1])
					f[r][i].insert(x&(s[r]-s[l-1]));
	printf("%lld",*f[n][k].rbegin());
}