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Introduction to arrays

Why do we need arrays?
Understanding the memory model
Overview of supported operations
Internal mechanics of arrays

Using arrays in code

Creating, reading and updating an array
Traversing an array
Everyday array building blocks
Common mistakes and how to avoid them

Solving problems with arrays

When is an array the right choice?
Reading constraints to pick an approach
The array problem-solving toolkit
How to dry run an array problem

Most asked interview questions

Two Sum
Move Zeroes
Best Time to Buy and Sell Stock
Majority Element
Sort 0s, 1s and 2s
Maximum Subarray Sum
Rotate Array
Product of Array Except Self
Find All Duplicates in an Array
Find Peak Element
Container With Most Water
3Sum
Subarray Sum Equals K
Increasing Triplet Subsequence
Kth Largest Element in an Array
Merge Intervals

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When is an array the right choice? | IntuitionRewire

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When is an array the right choice?

When is an array the right choice?

You now know why arrays exist and how to use them. This chapter is about when: recognising, from a problem statement, that an array is the right tool — and noticing when it isn't.

What arrays are great at

Reading and writing by position in O(1): "the 5th element", "the value at index i", "the cell at row r, column c".
Walking through everything in order, which is also very fast in practice: the elements sit side by side in memory, so the CPU's cache loads them in batches.
Storing data compactly: no pointers or extra bookkeeping per element.
Adding and removing at the end in O(1) (for growable arrays).

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Still to come

Signals in a problem statement
When an array is NOT the best tool
The array as a counter or lookup table
A quick self-test

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