Regular Expression Matching Leetcode Solution

/**
 * @param {string} s
 * @param {string} p
 * @return {boolean}
 */
const isMatch = function (s, p) {
  let memory = new Array(s.length + 1).fill(0).map((e) => new Array(p.length + 1).fill(-1))
  return memorySearch(s, 0, p, 0, memory)
}

const memorySearch = (s, i, p, k, memory) => {
  if (memory[i][k] != -1) return memory[i][k]
  if (k == p.length) return i == s.length

  let firstMatch = i < s.length && (s[i] == p[k] || p[k] == '.')
  if (k + 1 < p.length && p[k + 1] == '*') {
    memory[i][k] =
      (firstMatch && memorySearch(s, i + 1, p, k, memory)) || memorySearch(s, i, p, k + 2, memory)
  } else {
    memory[i][k] = firstMatch && memorySearch(s, i + 1, p, k + 1, memory)
  }
  return memory[i][k]
}