1014 Uniform Generator

Uniform Generator

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 28414 Accepted Submission(s): 11302

Problem Description

Computer simulations often require random numbers. One way to generate pseudo-random numbers is via a function of the form

seed(x+1) = [seed(x) + STEP] % MOD

where ‘%’ is the modulus operator.

Such a function will generate pseudo-random numbers (seed) between 0 and MOD-1. One problem with functions of this form is that they will always generate the same pattern over and over. In order to minimize this effect, selecting the STEP and MOD values carefully can result in a uniform distribution of all values between (and including) 0 and MOD-1.

For example, if STEP = 3 and MOD = 5, the function will generate the series of pseudo-random numbers 0, 3, 1, 4, 2 in a repeating cycle. In this example, all of the numbers between and including 0 and MOD-1 will be generated every MOD iterations of the function. Note that by the nature of the function to generate the same seed(x+1) every time seed(x) occurs means that if a function will generate all the numbers between 0 and MOD-1, it will generate pseudo-random numbers uniformly with every MOD iterations.

If STEP = 15 and MOD = 20, the function generates the series 0, 15, 10, 5 (or any other repeating series if the initial seed is other than 0). This is a poor selection of STEP and MOD because no initial seed will generate all of the numbers from 0 and MOD-1.

Your program will determine if choices of STEP and MOD will generate a uniform distribution of pseudo-random numbers.

Input

Each line of input will contain a pair of integers for STEP and MOD in that order (1 <= STEP, MOD <= 100000).

Output

For each line of input, your program should print the STEP value right- justified in columns 1 through 10, the MOD value right-justified in columns 11 through 20 and either “Good Choice” or “Bad Choice” left-justified starting in column 25. The “Good Choice” message should be printed when the selection of STEP and MOD will generate all the numbers between and including 0 and MOD-1 when MOD numbers are generated. Otherwise, your program should print the message “Bad Choice”. After each output test set, your program should print exactly one blank line.

Sample Input

3 5
15 20
63923 99999

Sample Output

     3         5    Good Choice    15        20    Bad Choice 63923     99999    Good Choice

代码

#include <iostream>#include <cstdio>using namespace std;int main(){    int a, b;    while (cin >> a >> b)    {        bool k = true;        for (int i = 2; i <= a&&i <= b; ++i)        {            if (!(a%i) && !(b%i))            {                k = false;                break;            }        }        if (k)            printf("%10d%10d    Good Choice\n\n", a, b);        else            printf("%10d%10d    Bad Choice\n\n", a, b);    }    return 0;}

死长死长的题，我这种英语渣渣的噩梦= =
这题叽里呱啦说这么多，其实就是让你判断是不是互质，那么就找有没有公约数
有几个容易忽视的地方：
1、格式，不然会各种pe
2、很多人都没有注意到，for循环里面要≤输入的数，这里举个例子大家就懂了：输入7和14

还有说cin和printf不能混用的，其实只要不关闭同步就可以混用，而同步默认都是开启的，这也会影响cin的性能。关闭同步的方法如下
std::ios::sync_with_stdio(false);