Hdu 2204 Eddy ' s hobby repulsion principle

Test instructions: Find out how many of the 1-n can be represented as m^k. (n<=10^18)

1. If I^b<=n (b>1), then (1~i) can be expressed in the form of m^k.

2. If the i^4<=n,i^4 can be represented by the (i^2) ^2, then the exponent is a prime number to represent all.

3. Because of the 2^60>10^18, it is only necessary to list the primes within 60.

4. If you simply follow the above to 60 primes (17) Each time pow (N,1.0/prime[i]) (I<17);

In this way, less consideration of duplication, such as 4^3 and 8^2, the exponent is a prime number they are 2^6;

So use the repulsion principle.

5, the direct radical will have the precision loss plus EPS = 1e-8 on the line;

#include <cstdio> #include <cstring> #include <iostream> #include <cmath>using namespace std;# Define ll __int64const Double EPS = 1e-8;ll prim[18]={2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59};ll n,ans;void dfs (ll index,ll len,ll s,ll num) {    if (Num==len)    {        ll temp= (Pow (n*1.0,1.0/s) +eps) -1;//is repeated every time 1^s is calculated, so subtract, and finally add one on the line        ans+=temp* (len &1?1:-1);        return;    }    if (index>=17) return;    if (s*prim[index]<=60)        dfs (index+1,len,s*prim[index],num+1);    DFS (index+1,len,s,num);} int main () {while    (scanf ("%i64d", &n)!=eof)    {        ans=0;        for (ll i=1;i<=3;i++)          Dfs (0,i,1,0);        printf ("%i64d\n", ans+1);    }    return 0;}

Hdu 2204 Eddy ' s hobby repulsion principle