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  • [hdu 4586] Play the Dice

    设dp[i]表示掷了i次的期望得分dp[1]=sigma(A[i])/N,dp[i]=dp[i-1]*M/N

    可以看出dp数组构成了一个等比数列

    ans=sigma(dp[i])=dp[1]*(1-(M/N)^n)/(1-M/N)

    当n趋近+oo时(M/N)^n趋近于0,则ans=dp[1]/(1-M/N)=sigma(A[i])/(N-M)

    特判当dp[1]!=0且N=M时ans=inf

     1 #include<bits/stdc++.h>
     2 using namespace std;
     3 #define maxn 205
     4 double A[maxn],B[maxn];
     5 int main(){
     6     int n,m;
     7     while(scanf("%d",&n)!=EOF){
     8         double all=0;
     9         for(int i=1;i<=n;i++){
    10             scanf("%lf",&A[i]);
    11             all+=A[i];
    12         }
    13         scanf("%d",&m);
    14         for(int i=1;i<=m;i++)
    15             scanf("%lf",&B[i]);
    16         if(all==0)printf("%.2lf
    ",0.0);
    17         else if(n==m)printf("inf
    ");
    18         else printf("%.2lf
    ",all/(n-m));
    19     }
    20     return 0;
    21 }
    View Code
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  • 原文地址:https://www.cnblogs.com/Ngshily/p/5516240.html
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