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23 lines
365 B
C++
23 lines
365 B
C++
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#include<iostream>
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using namespace std;
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long long C(int m,int n)
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{
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long long s=1;
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for(int i=n,j=1;j<=m;--i,++j)
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s=s*i/j;
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return s;
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}
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int main()
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{
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int n;
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long long ans;
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while(cin>>n)
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{
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ans=0;
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for(int i=2;i<=n;++i)
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ans+=C(i,n)*(i-1);
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cout<<ans<<endl;
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}
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return 0;
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}
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