Elo's rating algorithm

elo.cpp

#include<iostream>
#include<stdlib.h>
#include<math.h>
using namespace std;
int main()
{
	int tmp,i;
	double a[5],qa,qb,e;
	for(i=0;i<5;i++)
	a[i]=400;
	for(int j=0;j<5;j++)
	for(int k=j+1;k<5;k++)
		{
		cout<<"Enter "<<j+1<<" or "<<k+1<<" :";
		cin>>tmp;
		tmp--;
		qa=pow(10,(a[j]/400));
		qb=pow(10,(a[k]/400));
		if(j==tmp)
		{
			e=qa/(qa+qb);
			cout<<"EA="<<e;
			a[j]=a[j]+16*(1.0-e);
			e=qb/(qa+qb);
			cout<<"EB="<<e<<endl;
			a[k]=a[k]+16*(-e);
		}
		else
		{
			e=qb/(qa+qb);
			cout<<"EB="<<e;
			a[k]=a[k]+16*(1.0-e);
			e=qa/(qa+qb);
			cout<<"EA="<<e<<endl;
			a[j]=a[j]+16*(-e);
		}
		}
	for(i=0;i<5;i++)
	{
		cout<<"Rating for "<< i+1<<":"<<a[i]<<endl;
	}
	return 0;
}