多校6 1001 HDU5793 A Boring Question (推公式 等比数列求和)

题解：http://bestcoder.hdu.edu.cn/blog/

 多校6  HDU5793 A Boring Question

 // #pragma comment(linker, "/STACK:102c000000,102c000000")
 // #include <conio.h>
 #include <bits/stdc++.h>
 using namespace std;
 #define clc(a,b) memset(a,b,sizeof(a))
 const double inf = 0x3f3f3f3f;
 #define lson l,mid,rt<<1
 // #define rson mid+1,r,rt<<1|1
 const int N = ;
 const int MOD = 1e9+;
 #define LL long long
 #define LB long double
 // #define mi() (l+r)>>1
 double const pi = acos(-);
 const double eps = 1e-;
 void fre(){freopen("in.txt","r",stdin);}
 void freout(){freopen("out.txt","w",stdout);}
 inline int read(){int x=,f=;char ch=getchar();while(ch>''||ch<'') {if(ch=='-') f=-;ch=getchar();}while(ch>=''&&ch<='') { x=x*+ch-'';ch=getchar();}return x*f;}

 LL q_MOD(LL a,LL n)
 {
     LL ans=;
     while(n){
         if(n&)ans=ans*a%MOD;
         n>>=;
         a=a*a%MOD;
     }
     return ans;
 }
 int main()
 {
     int t;
     scanf("%d",&t);
     while(t--){
         LL n,m;
         scanf("%LLd%LLd",&n,&m);
         printf("%LLd\n",(q_MOD(m,n+)-)*q_MOD(m-,MOD-)%MOD);
     }
     return ;
 }