1017 Rate of Return

注意格式。

#include<iostream>#include<math.h>#include<stdio.h>using namespace std;struct word{int month;double depo;}wo[14];int N,month;double inve;double cal(double a){double sum=0;for(int i=0;i<N;i++){sum+=wo[i].depo*pow(a,wo[i].month);}return sum;}int main(){int numb=1;bool flag=0;while(cin>>N&&N!=-1){if(flag){cout<<endl;}for(int i=0;i<N;i++){cin>>month>>inve;wo[i].month=month;wo[i].depo=inve;}cin>>month>>inve;for(int i=0;i<N;i++){wo[i].month=month-wo[i].month+1;}double a=1.0;double b=2.0;double mid;  while(1){mid=(a+b)/2.0;if(b-a<0.000001)break;double cal_mid=cal(mid);if(cal_mid==inve)break;if(cal_mid>inve){b=mid;continue;}if(cal_mid<inve){a=mid;continue;}}mid=mid-1;cout<<"Case "<<numb++<<": ";printf("%.5lf\n",mid);flag=1;}return 0;}