Question

[python] Write a method that given a heap array returns the second smallest element in a heap.

Answer 1

import sys

  

def print2Smallest(arr):

  

    # There should be atleast two elements

    arr_size = len(arr)

    if arr_size < 2:

        print "Invalid Input"

        return

  

    first = second = sys.maxint

    for i in range(0, arr_size):

  

        # If current element is smaller than first then

        # update both first and second

        if arr[i] < first:

            second = first

            first = arr[i]

  

        # If arr[i] is in between first and second then

        # update second

        elif (arr[i] < second and arr[i] != first):

            second = arr[i];

  

    if (second == sys.maxint):

        print "No second smallest element"

    else:

        print ' second smallest element is',second

  

arr = [12, 13, 1, 10, 34, 1]

print2Smallest(arr)

The above code is efficient in finding the second smallest element and the first smallest element in the heap array.

Can also be done using extract-min for the heap 2 times. it will take o(1) time.