代码

#include<iostream>
using namespace std;
int n,m;
const int mod=1e9+7;
int ksm(int a,int n)
{
    int base=1;
    while(n)
    {
        if(n&1)
            base=1ll*base*a%mod;
        a=1ll*a*a%mod;
        n>>=1;
    }
    return base;
}
int main()
{
    cin>>n>>m;
    if(n>m)
        swap(n,m);
    if(n==1)
    {
        cout<<ksm(2,m);
        return 0;
    }
    if(n==2)
    {
        cout<<4ll*ksm(3,m-1)%mod;
        return 0;
    }    
    if(n==3)
    {
        cout<<112ll*ksm(3,m-3)%mod;
        return 0;
    }    
    if(n==4)
    {
        if(m==4)
            cout<<"912";
        else
            cout<<2688ll*ksm(3,m-5)%mod;
        return 0;
    }    
    if(n==5)
    {
        if(m==5)
            cout<<"7136";
        else
            cout<<21321ll*ksm(3,m-6)%mod;
        return 0;
    }    
    if(n==6)
    {
        if(m==6)
            cout<<"56768";
        else
            cout<<170112ll*ksm(3,m-7)%mod;
        return 0;
    }    
    if(n==7)
    {
        if(m==7)
            cout<<"453504";
        else
            cout<<1360128ll*ksm(3,m-8)%mod;
        return 0;
    }    
    if(n==8)
    {
        if(m==8)
            cout<<"3626752";
        else
            cout<<10879488ll*ksm(3,m-9)%mod;
        return 0;
    }    
}

评测结果