One-step write algorithm (shuffling algorithm)

 

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Playing card shuffling is a favorite game in our life. Is there any way for us to design a card shuffling method? There is a random function rand in the c Runtime Library, which can generate 0 ~ Any number between 32767. Is it possible to use such a function to immediately shuffles playing cards?

 

Here I will talk about the two algorithms that I have seen. You are welcome to talk about other methods.

 

(1) Global shuffling

 

The procedure is as follows:

 

A) first generate an array with the size of 54 and the initial value of 1 ~ 54

 

B) shuffles each index card according to the index 1 to 54. First, a remainder value = rand % 54 is generated. Then our index card is exchanged with this remainder card.

 

C) After Multiple indexes reach 54, a deck will be ready.

 

The Code is as follows:

 

 

Void get_rand_number (int array [], int length)

{

Int index;

Int value;

Int median;

 

If (NULL = array | 0 = length)

Return;

 

/* Allocate any data to be exchanged during each licensing */

For (index = 0; index <length; index ++ ){

Value = rand () % length;

 

Median = array [index];

Array [index] = array [value];

Array [value] = median;

}

}

Void get_rand_number (int array [], int length)

{

Int index;

Int value;

Int median;

 

If (NULL = array | 0 = length)

Return;

 

/* Allocate any data to be exchanged during each licensing */

For (index = 0; index <length; index ++ ){

Value = rand () % length;

 

Median = array [index];

Array [index] = array [value];

Array [value] = median;

}

}

 

 

 

 

(2) Local shuffling

The above algorithm is very simple, but there is a problem. We find that the cards we washed will be operated twice after each shuffling. I personally think it is a bit difficult to say, so we may wish to improve it:

 

A) Similarly, we first generate an array of 54 in size, which is arranged as 1 ~ 54

 

B) The index starts from 1 and ends at 54. This time the index card is only exchanged with the remaining cards that have not been washed, value = index + rand () % (54-index)

 

C) after all the index cards are washed, a deck will be ready.

 

The Code is as follows:

 

 

Void get_rand_number (int array [], int length)

{

Int index;

Int value;

Int median;

If (NULL = array | 0 = length)

Return;

/* Do not modify the allocated data during licensing */

For (index = 0; index <length; index ++ ){

Value = index + rand () % (length-index );

Median = array [index];

Array [index] = array [value];

Array [value] = median;

}

}

Void get_rand_number (int array [], int length)

{

Int index;

Int value;

Int median;

If (NULL = array | 0 = length)

Return;

/* Do not modify the allocated data during licensing */

For (index = 0; index <length; index ++ ){

Value = index + rand () % (length-index );

Median = array [index];

Array [index] = array [value];

Array [value] = median;

}

}

 

 

Note: I did not come up with the above two algorithms. You are welcome to contact me as the initial author of the algorithm. I will add the markup instructions in the article.