[topcoder]LongLongTripDiv2

http://community.topcoder.com/stat?c=problem_statement&pm=13091

解方程，对中国孩子太简单了。

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

class LongLongTripDiv2 {
public:
    string isAble(long long D, int T, int B) {
        long long diff = (D - T);
        if (diff % (B - 1) != 0)
            return "Impossible";
        long long b = diff / (B - 1);
        long long a = T - b;
        if (b >= 0 && a >= 0)
            return "Possible";
        return "Impossible";
    }
};