C ++为多米诺骨牌生成随机数

Question

My assignment involves writing several classes that will work together to randomly sort 28 dominoes for the user and display them. The main trouble I'm having so far is just creating the dominoes without any duplication. If you're familiar with dominoes, you know that each half of them are either blank or have 1-6 dots. Basically I'll have a dynamic array of 28 unique structs (dominoes) but I'm just stuck on generating these dominoes without having identical ones. I was thinking of using FOR loops to just go through and assign values within each struct but I figured there had to be some easier way.

This is what I have so far below; I know it's not much but I can't and don't want to go on with writing methods for sorting and display without getting this right first.

class CDominoes{
    public:
    struct Data
    {
        int top;
        int bottom;

        Data()
        {
            top = 0;
            bottom = 0;
        }
    } domino[28];

    //methods to assign spots to halves
};

Answer 1

The simplest solution is to generate, and then shuffle. To generate, you need to avoid wasting time generating duplicates. For example, (4,5) is the same as (5,4), so you don't want to generate both. That means that your inner loop should always begin at the current value of the outer loop. In so doing, you'll never repeat a combination. Here's an example:

int main () {
    for( int t = 0; t <= 6; ++t ) {
        for( int b = t; b <= 6; ++b ) {
            std::cout << "(" << t << "," << b << ")\n";
        }
    }
    return 0;
}

In this example, we're considering '0' to be the same as a blank domino.

Next, instead of printing these, put them into a random access container such as std::array or std::vector , and then use std::shuffle to shuffle your container.