Modular Equations

http://codeforces.com/contest/495/problem/B

a mod x = b等价于(a-b)%x=0那么就容易思考解决，不过我没想到这个也做出来了!

AC代码：

#include <math.h>#include <stdio.h>#include <string.h>#include <iostream>#include <algorithm>using namespace std;int main(){    int a,b; cin >> a >> b;    if(a < b){        cout << "0" << endl;        return 0;    }    if(a == b){        cout << "infinity" << endl;        return 0;    }    int t = a - b;    int ans = 0;    for(int k=1; k<=sqrt(t); k++){        if(t % k == 0 && (t / k > b))  ans++;        if(t % k == 0 && k*k != t && k > b) ans++;    }    cout << ans << endl;    //system("pause");    return 0;}