Sorting Methodologies
Sorting is process of arranging elements in a specific order to facilitate efficient searching, retrieval, and analysis of data.
Squares of a Sorted Array
Problem: Given a sorted array that may include negative numbers, return a new array of the squares in sorted order.
Approach: Use a two-pointer technique. Compare values from both ends of the array, place the larger square at the end of the result array, and move inward.
Key Point:
Sorting is avoided entirely by leveraging the structure of the input array.
Merge Two Sorted Linked Lists
Problem: Merge two sorted linked lists into a single sorted list.
Approach: Use a dummy node and two pointers. Compare nodes from both lists and attach the smaller one to the result.
Key Point:
This is efficient merging of already sorted data.
First and Last Occurrence in a Sorted Array
Problem: Find the first and last positions of a target value in a sorted array.
Approach: Perform binary search twice — once to find the left boundary and once to find the right boundary.
Key Point:
Sorting enables precise searching instead of scanning the entire array.
Search in Rotated Sorted Array
Problem: Search for a target value in a rotated sorted array.
Approach: Use a modified binary search. At each step, determine which half is sorted and decide if the target lies within that half.
Key Point:
Even when the array is rotated, partial ordering provides enough structure for efficient search.
Majority Element
Problem: Find the element that appears more than floor(n/2) times.
Approach: Use the Boyer–Moore Voting Algorithm to track a candidate and adjust its count.
Key Point:
Sorting is unnecessary. A linear-time algorithm solves the problem optimally.
Reverse and Deduplicate Linked Lists
Approach: Iteratively reverse pointers to flip the list.
Reverse Linked List:
Approach: Iteratively reverse pointers to flip the list.
Remove Duplicates:
Approach: Traverse the sorted list and skip adjacent duplicate nodes.
Key Point:
Sorting ensures duplicates are adjacent, making removal straightforward.
Sort a Linked List
Problem: Sort a linked list efficiently.
Approach: Use merge sort. Split the list using slow and fast pointers, recursively sort each half, and merge them.
Key Point:
Merge sort is preferred for linked lists because it does not require random access.
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