SRM 513 D1 250 YetAnotherIncredibleMachine

#include <algorithm>
#include <iostream>
#include <sstream>
#include <string>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <cstdio>
#include <cstdlib>
#include <cctype>
#include <cmath>
using namespace std;
typedef long long LL;
#define FOR(k,a,b) for(int k(a); k < (b); ++k)
#define REP(k,a) for(int k=0; k < (a); ++k)


class YetAnotherIncredibleMachine {
public:
    int countWays(vector <int> platformMount, vector <int> platformLength, vector <int> balls) {
        int n=platformMount.size();
        int b=balls.size();
        LL res=1;
        LL mod=1000000009;
        REP(i,n)
        {
            int ctr=0;
            FOR(j,-1*platformLength[i],1)
            {
                bool ok=true;
                REP(k,b)
                {
                    if(balls[k]>=platformMount[i]+j && balls[k]<=platformMount[i]+j+platformLength[i])
                    {
                        ok=false;
                        break;
                    }
                }
                if(ok)
                    ++ctr;
            }
            res*=ctr;
            res%=mod;
        }
        return res;
    }

};