hdu 1576

设(A/B)%9973=C，则A = 9973*k*B + B*C;得(B*C)%9973 = A % 9973;

C一定存在且唯一，所以只要穷举一下就找出来了。

/*
 * hdu1576/win.cpp
 * Created on: 2011-11-28
 * Author    : ben
 */
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <ctime>
#include <iostream>
#include <algorithm>
#include <queue>
#include <set>
#include <map>
#include <stack>
#include <string>
#include <vector>
#include <deque>
#include <list>
#include <functional>
#include <numeric>
#include <cctype>
using namespace std;

int main() {
#ifndef ONLINE_JUDGE
    freopen("data.in", "r", stdin);
#endif
    int T, B, _B, n;
    const int MOD = 9973;
    scanf("%d", &T);
    while(T--) {
        scanf("%d%d", &n, &B);
        _B = B % MOD;
        for(int c = 0; c < MOD; c++) {
            if((_B * c) % MOD == n) {
                printf("%d\n", c);
                break;
            }
        }
    }
    return 0;
}