mirror of
https://github.com/Kiritow/OJ-Problems-Source.git
synced 2024-03-22 13:11:29 +08:00
43 lines
699 B
C++
43 lines
699 B
C++
#include <iostream>
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using namespace std;
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const __int64 Mod=100000007;
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__int64 mod_exp(__int64 a,__int64 b0,__int64 n=Mod)
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{
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if( a > n )
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a %= n;
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__int64 i, d = 1, b[35];
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for( i=0; i < 35; ++i )
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{
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b[i] = b0%2;
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b0 /= 2;
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if( b0 == 0 )
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break;
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}
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for( ;i >= 0; --i )
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{
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d = (d*d)%n;
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if( b[i] == 1 )
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d = (d*a)%n;
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}
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return d;
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}
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__int64 solve (__int64 n,__int64 m)
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{
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__int64 ans=1;
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for (__int64 i=m*n+2-n;i<m*n+1;i++)
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{
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ans=((((ans*i)%Mod)*mod_exp(i-m*n+n-1,Mod-2)))%Mod;
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}
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ans=(ans*mod_exp(n,Mod-2))%Mod;
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return ans;
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}
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int main ()
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{
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__int64 n,m;
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while (scanf ("%I64d%I64d",&n,&m)!=EOF)
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{
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printf ("%I64d\n",solve(n,m));
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}
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return 0;
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}
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