放贷计算

#include <iostream>
#include <string.h>
#include <math.h>

using namespace std;

float totalLoan( int year,int pricipal,double rate,int err = 500)
{
    double monthfee = (double)pricipal/(12*year);
	int lyear = 0;
	int count = 0;
	double actualtotal = 0.0;
	double tmptotal = 0.0;
	double totalrate = 0.0;

	while(true)
	{
	    
		if( count > 5000)
			return -1.0;//quit 
		double totalloan = 0.0;
		lyear = 0;
		actualtotal = monthfee*12*year;
		tmptotal = pricipal;
		totalrate = 0.0;

        for( lyear = 0 ; lyear < year*12;lyear++ )
		{
	        totalrate += ( ( tmptotal  )*(rate) ) /12.0 ; 
			tmptotal = tmptotal - monthfee + ( (tmptotal)*rate )/12.0;
			//cout<<"lyear=="<<lyear<<"tmptotal=="<<tmptotal<<endl;
		}
		//cout<<"totalrate=="<<totalrate<<endl;
        
		totalloan = totalrate + pricipal;

		/*cout<<"totalloan=="<<totalloan<<endl;
		cout<<"monthfee*12*year=="<<monthfee*12*year<<endl;

		cout<<"err=="<<err<<endl;

        cout<<"totalloan - monthfee*12*year=="<<totalloan - monthfee*12*year<<endl;

		cout<<"monthfee*12*year - totalloan=="<<monthfee*12*year - totalloan<<endl;*/

		if( abs( totalloan - monthfee*12*year) < err )
		{
		    //cout<<"monthfee=="<<monthfee<<endl;
			//cout<<"totalfee=="<<monthfee*12*year<<endl;
			return monthfee*12*year;
		}

        if( totalloan - monthfee*12*year > err  )
		{
	        monthfee += (totalloan - monthfee*12*year)/( 12*year );
			//cout<<"monthfee++=="<<monthfee<<endl;
		}else if( totalloan - monthfee*12*year < err  )
		{
	        monthfee += (totalloan - monthfee*12*year)/( 12*year );
			//cout<<"monthfee--=="<<monthfee<<endl;
		}

		count++;
	}

}


void SummerFunction(int totalbackfee)
{
	int initbigFee = 0;
	double Alltotal = 0.0;
	double pretotal = 0.0;
	int tag = 0;
	int finalfee = 0;
    for( initbigFee = 10000 ;  initbigFee <= totalbackfee ; initbigFee += 10000 )
	{
	    int bigyear = 15;
		int bigfee = 280000 - initbigFee>0?280000 - initbigFee:0;
	    double rate = 0.049;
    
	    double bigtotal = totalLoan(bigyear,bigfee,rate);

        int smallyear = 10;
		int smallfee = 150000 - (totalbackfee - initbigFee) > 0?150000 - (totalbackfee - initbigFee):0;
	
	    double smalltotal = totalLoan(smallyear,smallfee,rate); 
		
		if( tag == 0 )
		{
		    pretotal =  bigfee +   smallfee;
			tag = 1;
		}
		
		Alltotal = bigtotal + smalltotal;

		if( pretotal > Alltotal  )
		{
		    finalfee =  initbigFee; 
			pretotal = Alltotal;
		}
		cout<<"总还贷"<<totalbackfee<<"大套还"<<initbigFee<<"总共还贷=="<<Alltotal<<"大套还贷=="<<bigtotal<<"小套还贷=="<<smalltotal<<endl;

	}
	cout<<"-------------------"<<endl;
    cout<<"最优还贷是大套还"<<finalfee<<endl;
	
	cout<<"这时公共还贷是=="<<pretotal<<endl;

	//totalLoan(15,30,0.0325); 

	cout<<"公积金还"<<totalLoan(15,300000,0.0325)<<endl;

}

int main()
{
    int fee = 250000; 

	//cout<<""
	//cin<<fee;
    SummerFunction(fee);
	return 0;

}