39 lines
750 B
C++
39 lines
750 B
C++
#include"stdio.h"
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#include"string.h"
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int main()
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{
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int n,m;
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int i;
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int a[101];
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int mark[101];
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int s1,s2;
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int max;
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while(scanf("%d%d",&n,&m)!=-1,n||m)
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{
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memset(mark,0,sizeof(mark));
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max=0;
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for(i=0;i<n;i++)
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{
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scanf("%d",&a[i]);
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mark[a[i]/m]++;
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if(max<a[i])max=a[i];
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}
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s2=max/m;
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max=0;
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for(i=0;i<=s2;i++)
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{
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if(mark[i]>max)
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max=mark[i];
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}
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s1=max;
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double ans;
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ans=0.01;
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for(i=0;i<=s2;i++)
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{
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ans+=(i*1.0/s2)*(mark[s2-i]*1.0/s1);
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}
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printf("%.6f\n",ans);
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}
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return 0;
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}
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