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Radix sort python

Radix sort python

def countingSortForRadix(inputArray, placeValue):
    # We can assume that the number of digits used to represent
    # all numbers on the placeValue position is not grater than 10
    countArray = [0] * 10
    inputSize = len(inputArray)

    # placeElement is the value of the current place value
    # of the current element, e.g. if the current element is
    # 123, and the place value is 10, the placeElement is
    # equal to 2
    for i in range(inputSize): 
        placeElement = (inputArray[i] // placeValue) % 10
        countArray[placeElement] += 1

    for i in range(1, 10):
        countArray[i] += countArray[i-1]

    # Reconstructing the output array
    outputArray = [0] * inputSize
    i = inputSize - 1
    while i >= 0:
        currentEl = inputArray[i]
        placeElement = (inputArray[i] // placeValue) % 10
        countArray[placeElement] -= 1
        newPosition = countArray[placeElement]
        outputArray[newPosition] = currentEl
        i -= 1
        
    return outputArray

def radixSort(inputArray):
    # Step 1 -> Find the maximum element in the input array
    maxEl = max(inputArray)

    # Step 2 -> Find the number of digits in the `max` element
    D = 1
    while maxEl > 0:
        maxEl /= 10
        D += 1
    
    # Step 3 -> Initialize the place value to the least significant place
    placeVal = 1

    # Step 4
    outputArray = inputArray
    while D > 0:
        outputArray = countingSortForRadix(outputArray, placeVal)
        placeVal *= 10  
        D -= 1

    return outputArray
    
input = [2,20,61,997,1,619]
print(input)
sorted = radixSort(input)
print(sorted)

0

Source: stackabuse.com

Radix sort in Python

# Radix sort in Python


# Using counting sort to sort the elements in the basis of significant places
def countingSort(array, place):
    size = len(array)
    output = [0] * size
    count = [0] * 10

    # Calculate count of elements
    for i in range(0, size):
        index = array[i] // place
        count[index % 10] += 1

    # Calculate cumulative count
    for i in range(1, 10):
        count[i] += count[i - 1]

    # Place the elements in sorted order
    i = size - 1
    while i >= 0:
        index = array[i] // place
        output[count[index % 10] - 1] = array[i]
        count[index % 10] -= 1
        i -= 1

    for i in range(0, size):
        array[i] = output[i]


# Main function to implement radix sort
def radixSort(array):
    # Get maximum element
    max_element = max(array)

    # Apply counting sort to sort elements based on place value.
    place = 1
    while max_element // place > 0:
        countingSort(array, place)
        place *= 10


data = [121, 432, 564, 23, 1, 45, 788]
radixSort(data)
print(data)

0

Source: programiz.com

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