写了个大概,你自己调试下
#include<iostream>
#include <iomanip>
# include <math.h>
using namespace std;
int main(int argc,char *argv[]){
int n;
float i;
cin>>n;
i=sqrt(n);
if(i*i==n)
cout<<int(i)<<endl;
else
cout.unsetf(ios::fixed);
cout<<fixed<<setprecision(2)<<float(i)<<endl;
return 0;
}