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https://github.com/Kiritow/OJ-Problems-Source.git
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16 lines
259 B
C++
16 lines
259 B
C++
#include <stdio.h>
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int main()
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{
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__int64 a[21];
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int i,n;
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a[1]=0;
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a[2]=1;
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while(scanf("%d",&n)!=EOF)
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{
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for(i=3;i<n+1;i++)
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{a[i]=(i-1)*(a[i-1]+a[i-2]);}
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printf("%I64d\n",a[n]);
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}
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return 0;
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}
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