#include<iostream>
#include<cstring>
#include<algorithm>
#include<cstdio>
#include<cmath>
using namespace std;


int sum, per, month;
double sp;
bool checkbiger(double x)
{
	return (1 - pow(1 / (1 + x), month)) / (1 - 1 / (1 + x)) >sp;
}

int main() 
{
	cin >> sum >> per >> month;
	//sum = 1000; per = 100; month = 12;
	sp = (double)sum / per;
	double l, r, mid;
	l = 0;
	r = 1000; //r最大为1000 % =》10
	//分成 [l,m-1][m,r]
	while (r - l >= 0.001)
	{
		mid = (l + r +1)/ 2;
		//mid = mid / 100;
		if (checkbiger(mid/100))
		{
			l = mid;
			//cout << l << endl;
		}
		else
			r = mid-1;
		//cout << "?" <<l<<" "<<r <<" "<<mid << endl;
	}
	printf("%.1f", l);
	//while (1);
	return 0;
}

不知道问题出现在什么地方，求大佬帮忙看看

只ac了13两个数据 又看不见测试数据