7_22_D题 Race to 1 Again（求期望）

7_22_D题 Race to 1 Again

题意

思路

代码

#include <iostream>
#include <cstdio>
#include <cstring>

using namespace std;
const int maxn = 1e5;
double E[maxn];

int init(){
E[1] = 0;
for(int i = 2 ; i <= maxn ; i ++){
double sum = 0;
int cnt = 0;
for(int k = 1 ; k*k <= i ; k ++){
if(i%k) continue;
sum += E[k];
cnt ++;
if(k*k != i){
sum += E[i/k];
cnt ++;
}
}
sum += cnt;
E[i] = sum/(cnt-1);
}
}

int main(){
init();
int T,kas= 1;;
cin >> T;
while(T --){
int d;
scanf("%d",&d);
printf("Case %d: %.9f\n",kas ++,E[d]);
}
return 0;
}