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Coding problem · Practical class design › Queues, stacks and history

Text editor with undo

mediumabout 35 minutes in an interview

Build the core of a plain-text editor as a TextEditor class.

new TextEditor() starts with empty text and the cursor at 0. The cursor sits between characters. 0 is before the first character, and text.length is after the last one.

Input: ed.type("helo"); ed.moveLeft(1); ed.type("l") [ed.getText(), ed.getCursor()] Output: ["hello", 4]
Input: ed.backspace(2) [ed.getText(), ed.getCursor()] Output: ["heo", 2]backspace returned 2

It comes in 3 parts, each building on the last: Typing and the cursor, Undo, Redo.