TopCoder High School SRM 19 Level one - 250 pt - Dart Throw solution

TopCoder High School SRM 19 Level one - 250 pt - Dart Throw statement: http://community.topcoder.com/stat?c=problem_statement&pm=6786&rd=10071

TopCoder High School SRM 19 Level one - 250 pt - Dart Throw editorial: http://community.topcoder.com/tc?module=Static&d1=hs&d2=match_editorials&d3=hs_srm19

TopCoder High School SRM 19 Level one - 250 pt - Dart Throw solution: 

#include <iostream>
#include <vector>
using namespace std;

class DartThrow {
    public: double bestScore(vector <int> py, int pr) {
        double cnt=0, ma=0, a;
        a=(double)pr/100;
        for(int i=0; i<py.size(); i++) {
            if(i==0) cnt=a*py[i] + (1-a)/2*py[(i+1)%py.size()] + (1-a)/2*py[py.size()-1];
            else cnt=a*py[i] + (1-a)/2*py[(i+1)%py.size()] + (1-a)/2*py[(i-1)];
            if(cnt>ma) ma=cnt;
        }   
        return ma;
    }
};