mirror of
https://git.sb/baoshuo/OI-codes.git
synced 2024-12-25 18:12:04 +00:00
47 lines
1.1 KiB (Stored with Git LFS)
C++
47 lines
1.1 KiB (Stored with Git LFS)
C++
#include<bits/stdc++.h>
|
|
using namespace std;
|
|
#define rep(i,x,y) for (int i=(x);i<=(y);i++)
|
|
#define drep(i,y,x) for (int i=(y);i>=(x);i--)
|
|
#define pii pair<int,int>
|
|
#define fir first
|
|
#define sec second
|
|
#define MP make_pair
|
|
#define templ template<typename T>
|
|
templ bool chkmin(T &x,T y){return x>y?x=y,1:0;}
|
|
templ bool chkmax(T &x,T y){return x<y?x=y,1:0;}
|
|
void file() {
|
|
#ifdef NTFOrz
|
|
freopen("a.in","r",stdin);
|
|
#endif
|
|
}
|
|
typedef long long ll;
|
|
#define mod 1000000007ll
|
|
#define sz 101010
|
|
|
|
int n,m;
|
|
int a[sz];
|
|
ll pw[sz];
|
|
|
|
ll SS(ll n){return n*(n-1)/2%mod;}
|
|
|
|
int main() {
|
|
cin>>n>>m;
|
|
ll S=0;
|
|
rep(i,1,n) cin>>a[i],(S+=a[i])%=mod;
|
|
pw[0]=1; rep(i,1,sz-1) pw[i]=pw[i-1]*2%mod;
|
|
ll ans=0;
|
|
rep(i,1,m) {
|
|
ll sum=S*pw[i-1]%mod;
|
|
ll W=sum*(n*pw[i]%mod+1)%mod;
|
|
sum=sum*2%mod;
|
|
ll res=W*pw[m-i]%mod+sum*SS(pw[m-i])%mod*pw[i]%mod*n%mod;
|
|
chkmax(ans,res%mod);
|
|
}
|
|
ll sum=S;
|
|
ll W=0; rep(i,1,n) (W+=1ll*a[i]*(n-i+1)%mod)%=mod;
|
|
ll res=W*pw[m]%mod+sum*SS(pw[m])%mod*n%mod;
|
|
chkmax(ans,res%mod);
|
|
cout<<ans;
|
|
return 0;
|
|
}
|