The Runtime Theory
hardLeetCode#dynamic-programming#strings

Regular Expression Matching

Implement full-string matching with dot for any character and star for zero or more copies of its preceding token.

The Runtime Theory Team25 min read
Solve it

Solving happens on the judge — come back and mark it done

Sample cases

ins="aa", p="a"

outfalse

ins="aa", p="a*"

outtrue

ins="ab", p=".*"

outtrue

Implement full-string matching with dot for any character and star for zero or more copies of its preceding token.

A good solution should

  • State the invariant or decision rule that makes the approach correct.
  • Explain time and space costs in terms of input size and required output.
  • Handle empty, minimal, duplicate, and boundary-shaped inputs.

Reasoning prompt

For star, consider zero uses or one-more use of its preceding token. Matching must consume the entire input.

Use the linked judge for the canonical challenge. The examples above are compact TRT checks; create additional tests around the boundary most likely to break your invariant.

More practice in this topic

One dispatch a week

The trace behind each problem, the tradeoff that explains it, and one technical dispatch per week — no noise.

One technical dispatch per week. No noise.

Not started

Sign in to save your learning progress.

Sign in to save