Python Program for Counting Sort
Counting sort is a sorting technique based on keys between a specific range. It works by counting the number of objects having distinct key values (kind of hashing). Then doing some arithmetic to calculate the position of each object in the output sequence.
# Python program for counting sort # The main function that sort the given string arr[] in # alphabetical order def countSort(arr): # The output character array that will have sorted arr output = [0 for i in range(256)] # Create a count array to store count of inidividul # characters and initialize count array as 0 count = [0 for i in range(256)] # For storing the resulting answer since the # string is immutable ans = ["" for _ in arr] # Store count of each character for i in arr: count[ord(i)] += 1 # Change count[i] so that count[i] now contains actual # position of this character in output array for i in range(256): count[i] += count[i-1] # Build the output character array for i in range(len(arr)): output[count[ord(arr[i])]-1] = arr[i] count[ord(arr[i])] -= 1 # Copy the output array to arr, so that arr now # contains sorted characters for i in range(len(arr)): ans[i] = output[i] return ans # Driver program to test above function arr = "geeeeeeeeeeeeeeeeeksfoooooooooooooooooorgggggggggggggggeeks"ans = countSort(arr) print "Sorted character array is %s" %("".join(ans)) # |
Output:
Sorted character array iseeeeeeeeeeeeeeeeefggggggggggggggggkkoooooooooooooooooorss