Python Program for Cycle Sort

In this article, we will learn about the solution to the problem statement given below.

Problem statement − We are given an array, we need to sort it using the concept of cycle sort.

It is an in-place algorithm and swapping takes place by the formation of cycles.

Now let’s observe the solution in the implementation below −

Example

 Live Demo

def cycleSort(array):
   writes = 0
   # cycles to be rotated
   for cycleStart in range(0, len(array) - 1):
      item = array[cycleStart]
      #position to place the item
      pos = cycleStart
      for i in range(cycleStart + 1, len(array)):
         if array[i] < item:
            pos += 1
      # if item exits, it is not a cycle
      if pos == cycleStart:
         continue
      # Otherwise, place the item
      while item == array[pos]:
         pos += 1
      array[pos], item = item, array[pos]
      writes += 1
      # rotation continued
      while pos != cycleStart:
         # Find a position to place the item
         pos = cycleStart
         for i in range(cycleStart + 1, len(array)):
            if array[i] < item:
               pos += 1
         # place the item
         while item == array[pos]:
            pos += 1
         array[pos], item = item, array[pos]
         writes += 1
   return writes
# main
arr = [1,5,3,4,8,6,3,4,5]
n = len(arr)
cycleSort(arr)
print("Sorted array is : ")
for i in range(0, n) :
   print(arr[i], end = " ")

Output

Sorted array is :
1 3 3 4 4 5 5 6 8

All the variables are declared in the local scope and their references are seen in the figure above.

Conclusion

In this article, we have learned about how we can make a Python Program for Cycle Sort