SDE - Intern

You are given a number 'N' in the form of a string 'S', which is a palindrome. You need to find the greatest number strictly less than 'N' which is also a palindrome.

Note:

1. A palindrome is a word, number, phrase, or another sequence of characters that reads the same backward as forward, such as madam, racecar, 1234321, etc.
2. The numerical value of the given string S will be greater than 0.
3. A single-digit number is also considered a palindrome.
4. The answer number should not contain any leading zeros, except for the case when the answer is 0.
5. Note that the length of the string is nothing but the number of digits in N.

Explain how heaps are implemented

Diamond problem is when more than one class inherits a class and one class inherits those classes. Ex. Classes B and C inherit class A, and class D inherits classes B and C. If B and C have the same function and class D calls that function, then there will be an error as the compiler won't know which class's function to call.

You’re given a stack consisting of 'N' integers. Your task is to sort this stack in descending order using recursion.

We can only use the following functions on this stack S.

is_empty(S) : Tests whether stack is empty or not.
push(S) : Adds a new element to the stack.
pop(S) : Removes top element from the stack.
top(S) : Returns value of the top element. Note that this function does not remove elements from the stack.

Note :

1) Use of any loop constructs like while, for..etc is not allowed. 
2) The stack may contain duplicate integers.
3) The stack may contain any integer i.e it may either be negative, positive or zero.