Problem Statement We have to implement the reorderList function that takes the head node of a linked list as input and reorders its nodes in the format specified below. Given an input list like the following: $$Node_0 \rightarrow Node_1 \rightarrow Node_2 \rightarrow \dots \rightarrow Node_{(n-2)} \rightarrow Node_{(n-1)} \rightarrow Node_n$$ the reorderList function should reorder its nodes as: $$Node_0 \rightarrow Node_n \rightarrow Node_1 \rightarrow Node_{(n-1)} \rightarrow Node_2 \rightarrow Node_{(n-2)} \rightarrow \dots$$...

February 15, 2024 · 7 min · Avnish

## Merge Two Sorted Linked Lists

Problem Statement We have to implement the mergeTwoLists function that takes the head nodes of two sorted linked lists as input and returns the head node of the merged linked list as the output. Optimal Solution To merge both linked lists we can use the two-pointer approach by maintaining an iterator on both linked lists and comparing their values. The smaller value will be selected and inserted at the end of a new list....

January 29, 2024 · 4 min · Avnish

Problem Statement We have to implement the reverseList function that takes the head node of a linked list as an input and returns the head node of the reversed linked list in the output. Brute Force Solution If we iterate over the input linked list and insert its value at the beginning of a new list the result would be a reversed linked list. Psuedo-code for the Brute Force Solution reversedLinkedList = LinkedList() temp = linked_list....

January 26, 2024 · 4 min · Avnish

## Two-Pointer Approach

To solve problems like Two Sums, Product Except Self, or Contains Duplicate we have to access multiple values at the same time from a sequential data structure (for example, a Linked List or an Array). The initial instinct while solving these problems is to use nested loops where each layer of the loop will maintain a different iterator on the data structure. But this approach does not scale well with the size of input as a single order of nested loops has $O(n^2)$ worst-case time complexity....

January 23, 2024 · 7 min · Avnish