世界上最好的题解😄

#include<bits/stdc++.h>
using namespace std;
int a,b,c;
bool check(double p){
	double s=0,t=(1+p);
	for(int i=1;i<=c;i++){
		s+=b/t;
		t*=(1+p);
	}
	return s<=a;
}
double bsearch(double l,double r){
	while(r-l>=1e-5){
		double mid=(l+r)/2;
		if(check(mid))r=mid;
		else l=mid;
	}
	return l;
}
int main(){
	cin>>a>>b>>c;
	double l=0,r=10;
	double ans=bsearch(l,r);
	printf("%.1lf",ans*100);
	return 0;
}

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