看了老半天才懂

#include<bits/stdc++.h>
using namespace std;
double f(double x,double n){
	if(n==1){
		return sqrt(1+x);
	}else{
		return sqrt(n+f(x,n-1));
	}
}
int main(){
	double x,n;
	cin>>x>>n;
	printf("%.2lf",f(x,n));
	return 0;
}