42 lines
835 B
C++
42 lines
835 B
C++
#include <iostream>
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#include <cstring>
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#include <string>
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#include <cstdio>
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#include <cmath>
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#include <algorithm>
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#include <vector>
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#include <queue>
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#include <map>
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#include<stack>
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using namespace std;
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typedef long long ll;
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const double eps=0.0000000000001;
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double dp[1000005];
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int main()
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{
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int n,m;
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while(~scanf("%d%d",&m,&n))
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{
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int flag=1;
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memset(dp,0,sizeof(dp));
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dp[0]=1.0;
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dp[1]=1.0/m;
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for(int i=2;i<=n;i++)
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{
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dp[i]+=dp[i-1]*(m+1)/m;
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if(i-1-m>=0)
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dp[i]-=dp[i-1-m]/m;
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if(fabs(dp[i]-dp[i-1])<eps)
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{
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printf("%.5lf\n",dp[i]);
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flag=0;
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break;
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}
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}
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if(flag)
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{
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printf("%.5lf\n",dp[n]);
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}
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}
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}
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