ACdream 1007

input

T           <=10

n k            n<=1000         k<=10^18

a1,a2,...an                |ai|<=10^18

output

(a1^k+a2^k+...+an^k)%10^10+7

Sample Input

2

3 1

1 2 3

3 10

1 2 3

Sample Output

6 60074

做法：快速幂+__int128,需注意ai可能是负数，模的是10^10+9，超int了

模乘法：对一个数可以拆分为N=（P*(N/P)+(N%P)）

 #include <bits/stdc++.h>
 #define MAX 100000
 #define LL long long
 //#define __int128 long long
 #define mod 10000000007LL
 using namespace std;
 int cas=,T;
 template <class T>
 bool scanff(T &ret)
 { //Faster Input
     char c; int sgn; T bit=0.1;
     if(c=getchar(),c==EOF) return ;
     while(c!='-'&&c!='.'&&(c<''||c>'')) c=getchar();
     sgn=(c=='-')?-:;
     ret=(c=='-')?:(c-'');
     while(c=getchar(),c>=''&&c<='') ret=ret*+(c-'');
     if(c==' '||c=='\n'){ ret*=sgn; return ; }
     while(c=getchar(),c>=''&&c<='') ret+=(c-'')*bit,bit/=;
     ret*=sgn;
     return ;
 }
 template <class T>
 void printff(T ret)
 { //Faster Output
     char s[];
     if(ret<) { printf("-");ret=-ret; }
     int len=;
     while(ret)
     {
         s[++len]=ret%+'';
         ret/=;
     }
     if(!len) s[++len]='';
     while(len)
     {
         printf("%c",s[len]);
         len--;
     }
 }
 LL qmod( __int128 a, LL n)
 {
     __int128 res=;
     LL flag=;
     if(a<) { flag=(n&?-:);a=-a; }
     a%=mod;
     while(n)
     {
         if(n&) res=res*a%mod;
         a=a*a%mod;
         n>>=;
     }
     return (LL)res*flag;
 }
 int main()
 {
     //freopen("1.in","w",stdout);
     //freopen("1.in","r",stdin);
     //freopen("1.out","w",stdout);
     scanf("%d",&T);
     while(T--)
     {
         int n;
         LL k,a,res=;
         scanf("%d%lld",&n,&k);
         for(int i=;i<n;i++)
         {
             scanf("%lld",&a);
             res=(res+qmod(a,k))%mod;
         }
         printff((res+mod)%mod);
         printf("\n");
     }
     //printf("time=%.3lf",(double)clock()/CLOCKS_PER_SEC);
     return ;
 }