Shuffling

You have an array of numbers, how do you shuffle them?
Or, You have a playlist of songs how do you shuffle them?

The shuffling method is called
Fisher yates shuffling
The method is you take the array then generate a random number from 0 to len(array) take the number in that index(remove the number) and put this number in another array. Now do exactly same with the new array with one less element.

You can do this in place also: The modification is simple you take the number by the index generated in first step and then put this number in the end of the array (swap the end number of the array with the index generated.

in Python shuffling is done by


import random
list = [i for i in range(1,53)]
random.shuffle(list)

Fisher yates

We can implement fisher yates in place:


import random
li = [i for i in range(1,53)]

#generate a random number in range 0,52(exclusive)
for i in range(52):
  index = random.randint(0,51-i)
  temp = li[index]
  li[index] = li[52-i - 1]
  li[52-i-1] = temp

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