# Build a Basic Regex Parser Aced (formerly Exponent) publishes a public search API over its indexed pages; the guide is at https://www.aced.io/agents/agent-access. Source: https://www.aced.io/questions/3064/build-basic-regex-parser Source observed: 2026-11-05T00:29:21.341Z Last checked: 2026-11-05T00:29:21.341+00:00 Indexed: 2026-11-07T03:53:57.016+00:00 --- # Build a Basic Regex Parser **Difficulty:** Hard **Question type:** Data Structures & Algorithms; Coding **Associated roles:** [Machine Learning Engineer](https://www.aced.io/questions?role=ml-engineer), [Software Engineer](https://www.aced.io/questions?role=swe), [Data Engineer](https://www.aced.io/questions?role=data-engineer) **Associated companies:** [Apple](https://www.aced.io/questions?company=apple), [Nvidia](https://www.aced.io/questions?company=nvidia), [Adobe](https://www.aced.io/questions?company=adobe) ## Problem Implement a regular-expression function `isMatch` that accepts two strings, `text` and `pattern`, and returns `true` when the entire text matches the pattern as a regular expression. For this exercise, the literal symbols `.` and `*` do not occur in `text`; they are special symbols only in `pattern`. The supported pattern syntax is: - `.` matches exactly one character, acting as a wildcard. - `*` matches a sequence of zero or more characters represented by the immediately preceding letter. Explain your algorithm and analyze its time and space complexity. A regular-expression refresher is referenced as “[link to strings lesson here]” in the exercise text. ## Examples | Text | Pattern | Output | |---|---|---:| | `"aa"` | `"a"` | `false` | | `"aa"` | `"aa"` | `true` | | `"abc"` | `"a.c"` | `true` | | `"abbb"` | `"ab*"` | `true` | | `"acd"` | `"ab*c."` | `true` | ## Practice interface We provide Question, Solution, and Community tabs, along with Hint 1, Hint 2, Hint 3, Challenge 1, and Challenge 2 controls. The coding workspace includes Editor and Share views, with Output, Test Results, and Console panels. 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