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27 lines
472 B
C++
27 lines
472 B
C++
#include <algorithm>
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#include <iostream>
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#include <iomanip>
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#include <cstring>
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#include <cstdio>
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#include <stack>
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#include <ctime>
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#include <cmath>
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#include <queue>
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typedef long long l;
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typedef double d;
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typedef char c;
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using namespace std;
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int s(int a,int b,int c){
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int sum=0;
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for(int i=a;i<=b;i+=c){
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sum+=i;
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}
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return sum;
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}
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int main(){
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int a,b,c;
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cin >>a>>b>>c;
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cout <<fixed<<setprecision(3)<<s(a,b*10,c)*1.0/(s(a,b*2,c*1.0/2)*s(a*1.0/2,b-a,c*2));
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return 0;
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}
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