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

 1 多校6 1001 HDU5793 A Boring Question
 2 
 3 
 4 // #pragma comment(linker, "/STACK:102c000000,102c000000")
 5 // #include <conio.h>
 6 #include <bits/stdc++.h>
 7 using namespace std;
 8 #define clc(a,b) memset(a,b,sizeof(a))
 9 const double inf = 0x3f3f3f3f;
10 #define lson l,mid,rt<<1
11 // #define rson mid+1,r,rt<<1|1
12 const int N = 2010;
13 const int MOD = 1e9+7;
14 #define LL long long
15 #define LB long double
16 // #define mi() (l+r)>>1
17 double const pi = acos(-1);
18 const double eps = 1e-8;
19 void fre(){freopen("in.txt","r",stdin);}
20 void freout(){freopen("out.txt","w",stdout);}
21 inline int read(){int x=0,f=1;char ch=getchar();while(ch>‘9‘||ch<‘0‘) {if(ch==‘-‘) f=-1;ch=getchar();}while(ch>=‘0‘&&ch<=‘9‘) { x=x*10+ch-‘0‘;ch=getchar();}return x*f;}
22 
23 LL q_MOD(LL a,LL n)
24 {
25     LL ans=1;
26     while(n){
27         if(n&1)ans=ans*a%MOD;
28         n>>=1;
29         a=a*a%MOD;  
30     }
31     return ans;
32 }
33 int main()
34 {
35     int t;
36     scanf("%d",&t);
37     while(t--){
38         LL n,m;
39         scanf("%LLd%LLd",&n,&m);
40         printf("%LLd\n",(q_MOD(m,n+1)-1)*q_MOD(m-1,MOD-2)%MOD);
41     }
42     return 0;
43 }