Gym - 100941G

Gym - 100941G

https://vjudge.net/problem/Gym-100941G
比赛的时候真的是不会啊，那就没办法了。
结论：每x周减一次头发，第k次剪发时的头发长度为x^k。
x^k=L,x=L^(1/k)
ans=kx=k*L^(1/k)

#include <iostream>
#include <cstdio>
#include <queue>
#include <algorithm>
#include <cmath>
#include <cstring>
#define inf 2147483647
#define N 1000010
#define p(a) putchar(a)
#define For(i,a,b) for(int i=a;i<=b;++i)

using namespace std;
double ans,L;
void in(int &x){
    int y=;char c=getchar();x=;
    while(c<''||c>''){if(c=='-')y=-;c=getchar();}
    while(c<=''&&c>=''){ x=(x<<)+(x<<)+c-'';c=getchar();}
    x*=y;
}
void o(int x){
    if(x<){p('-');x=-x;}
    if(x>)o(x/);
    p(x%+'');
}

signed main(){
    freopen("princess.in","r",stdin);
    freopen("princess.out","w",stdout);
    cin>>L;
    ans=1e9;
    For(k,,)
        ans=min(ans,(double)k*pow(L,1.0/(double)k));
    printf("%.6f",ans);
    return ;
}