Merge pull request #332 from rohansrivastava5491/patch-1

Added radix_Sort.py

Author: gantavyamalviya

Python/radix_sort.py

@@ -0,0 +1,56 @@
+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)