Sort a stack using a temporary stack - cook the code

Thursday, 28 December 2017

Sort a stack using a temporary stack

Sort a stack using a temporary stack

Given a stack of integers, sort it in ascending order using another temporary stack.
Examples:
Input : [34, 3, 31, 98, 92, 23]
Output : [3, 23, 31, 34, 92, 98]

Input : [3, 5, 1, 4, 2, 8]
Output : [1, 2, 3, 4, 5, 8]

We follow this algorithm.

  1. Create a temporary stack say tmpStack.
  2. While input stack is empty do this:
    • Pop an element from input stack call it x
    • while temporary stack is not empty and top of stack is greater than x,
      pop from temporary stack and push it to the input stack
    • push temp in tempory of stack
  3. The sorted numbers are in tmpStack
Here is a dry run of above pseudo code.
input: [34, 3, 31, 98, 92, 23]

Element taken out: 23
input: [34, 3, 31, 98, 92]
tmpStack: [23]

Element taken out: 92
input: [34, 3, 31, 98]
tmpStack: [23, 92]

Element taken out: 98
input: [34, 3, 31]
tmpStack: [23, 92, 98]

Element taken out: 31
input: [34, 3, 98, 92]
tmpStack: [23, 31]

Element taken out: 92
input: [34, 3, 98]
tmpStack: [23, 31, 92]

Element taken out: 98
input: [34, 3]
tmpStack: [23, 31, 92, 98]

Element taken out: 3
input: [34, 98, 92, 31, 23]
tmpStack: [3]

Element taken out: 23
input: [34, 98, 92, 31]
tmpStack: [3, 23]

Element taken out: 31
input: [34, 98, 92]
tmpStack: [3, 23, 31]

Element taken out: 92
input: [34, 98]
tmpStack: [3, 23, 31, 92]

Element taken out: 98
input: [34]
tmpStack: [3, 23, 31, 92, 98]

Element taken out: 34
input: [98, 92]
tmpStack: [3, 23, 31, 34]

Element taken out: 92
input: [98]
tmpStack: [3, 23, 31, 34, 92]

Element taken out: 98
input: []
tmpStack: [3, 23, 31, 34, 92, 98]

final sorted list: [3, 23, 31, 34, 92, 98]
Output:
Sorted numbers are:
98 92 34 31 23 3 


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