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https://github.com/Kiritow/OJ-Problems-Source.git
synced 2024-03-22 13:11:29 +08:00
19 lines
371 B
C++
19 lines
371 B
C++
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#include<stdio.h>
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int main()
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{
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int n,i;
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double a1,an,c[3001],s,x;
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while(~scanf("%d",&n))
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{
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scanf("%lf%lf",&a1,&an);
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for(i=1;i<=n;i++)
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scanf("%lf",&c[i]);
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s=n*a1+an;x=0;
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for(i=1;i<=n;i++)
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x+=(n-i+1)*c[i];
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s=(s-2*x)/(n+1);
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printf("%.2lf\n",s);
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}
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return 0;
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}
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