DP World SDE-2 Interview Questions and Answers

Round duration - 60 Minutes
Round difficulty - Medium

It was technical discussion plus coding round

Q1. 
Count Ways To Reach The N-th Stair Problem Statement
You are given a number of stairs, N. Starting at the 0th stair, you need to reach the Nth stair. Each time you can either climb one step or two steps. ...read more
Ans. 
The problem involves finding the number of distinct ways to climb to the Nth stair by taking one or two steps at a time.
• Use dynamic programming to solve this problem efficiently.

• The number of ways to reach the Nth stair is the sum of the number of ways to reach the (N-1)th stair and the (N-2)th stair.

• Handle large inputs by taking modulo 10^9+7 of the result.

• Example: For N=3, there are 3 ways to climb to the third stair
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Q2. 
Clone a Linked List with Random Pointers
You are provided with a linked list where each node has two pointers. The first pointer directs to the next node, and the second one, known as the 'random' pointer...read more
Ans. 
Clone a linked list with random pointers and return the head of the copied list.
• Create a deep copy of the linked list by iterating through each node and creating a new node with the same value.

• Update the random pointers of the new nodes based on the random pointers of the original list.

• Use a hashmap to keep track of the mapping between original nodes and their corresponding new nodes.

• Return the head of the copied list.
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