SDE - Intern

You have been given an array/list of integers 'ARR' of size 'N'. Your task is to find two things-

1. The number of elements that are occurring an Odd number of times.

2. The number of elements that are occurring Even a number of times.

For Example:

ARR = [2, 1, 2, 1, 5, 5, 2]    
Output: 1 2 

2 occurs three(odd) times.
1 occurs two(even) times.
5 occurs two(even) times.

So, the total 1 element is occurring an odd number of times and 2 elements are occurring an even number of times.

You are given a linked list of integers where each node has two fields: data field which contains a value, 'next' field which points to its adjacent node to the right or NULL if it is the last node. Your task is to delete all such nodes X, whose adjacent nodes to the right have strictly greater value than the value of X.

A singly linked list is a linear data structure in which we can traverse only in one direction i.e. from Head to Tail. It consists of several nodes where each node contains some data and a reference to the next node.

A sample Linked List-

Follow Up:

Can you solve this in linear time and constant space complexity?