Solving Regular Expression Matching in Javascript. Please try yourself first to solve the problem and submit your implementation to LeetCode before looking into solution.

Problem Description

Given an input string (s) and a pattern (p), implement regular expression matching with support for '.' and '*'.

  • '.' Matches any single character.
  • '*' Matches zero or more of the preceding element.
  • The matching should cover the entire input string (not partial).

Note:

  • s could be empty and contains only lowercase letters a-z.
  • p could be empty and contains only lowercase letters a-z, and characters like . or *.

Example 1:

Input:
s = "aa"
p = "a"

Output: false

Explanation: "a" does not match the entire string "aa".

Example 2:

Input:

s = "aa"
p = "a*"
Output: true

Explanation: '*' means zero or more of the precedeng element, 'a'. Therefore, by repeating 'a' once, it becomes "aa".

Example 3:

Input:
s = "ab"
p = ".*"
Output: true

Explanation: "." means "zero or more () of any character (.)".

Example 4:

Input:
s = "aab"
p = "cab"
Output: true

Explanation: c can be repeated 0 times, a can be repeated 1 time. Therefore it matches "aab".

Example 5:

Input:
s = "mississippi"
p = "misisp*."
Output: false

See the full details of the problem Regular Expression Matching at LeetCode

Originally posted at: @github.com/ignacio-chiazzo/Algorithms-Leetcode-Javascript