Arrays & Two Pointers — Free DSA Tutorial
Learn Arrays & Two Pointers in DSA with a free, beginner-friendly tutorial, examples and practice for Indian students on Syllab.in.
TL;DR: Learn Arrays & Two Pointers in DSA with a free, beginner-friendly tutorial, examples and practice for Indian students on Syllab.in.
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Arrays & Two Pointers in DSA
An array stores elements in contiguous memory, so accessing any index is O(1). In Python we use a list. Reading/updating by index is O(1); searching for a value is O(n); inserting or deleting in the middle is O(n) because later elements must shift.
The two-pointer technique is a cornerstone pattern: use two indices that move toward each other (or in the same direction) to solve problems in O(n) instead of O(n²). It works beautifully on sorted arrays — e.g. checking if two numbers add up to a target, or reversing in place.
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