0010. Regular Expression Matching.js

// 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 preceding 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 = "c*a*b"
// 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 = "mis*is*p*."
// Output: false


// 1) 递归
/**
 * @param {string} s
 * @param {string} p
 * @return {boolean}
 */
const isMatch = (s, p) => {
  if (p.length === 0) return s.length === 0;
  const firstMatch = s.length > 0 && (p[0] === s[0] || p[0] === ".");
  if (p.length >= 2 && p[1] === "*") {
    return isMatch(s, p.slice(2)) || (firstMatch && isMatch(s.slice(1), p));
  } else {
    return firstMatch && isMatch(s.slice(1), p.slice(1));
  }
}


// 2) 动态规划