10.regular-expression-matching.js

/*
 * @lc app=leetcode id=10 lang=javascript
 *
 * [10] Regular Expression Matching
 *
 * https://leetcode.com/problems/regular-expression-matching/description/
 *
 * algorithms
 * Hard (25.73%)
 * Likes:    3113
 * Dislikes: 580
 * Total Accepted:    344.9K
 * Total Submissions: 1.3M
 * Testcase Example:  '"aa"\n"a"'
 *
 * 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
 * 
 * 
 */

// @lc code=start
/**
 * @param {string} s
 * @param {string} p
 * @return {boolean}
 */
var isMatch = function (s, p) {
    const container = {};

    const match = (sId, pId) => {
        if (container[`${sId}:${pId}`] !== undefined) return container[`${sId}:${pId}`];
        if (sId > s.length) return false;
        if (sId === s.length && pId === p.length) return true;

        if (p[pId] === '.' || p[pId] === s[sId]) {
            container[`${sId}:${pId}`] = p[pId + 1] === '*' ?
                match(sId + 1, pId) || match(sId, pId + 2) :
                match(sId + 1, pId + 1);

        } else {
            container[`${sId}:${pId}`] = p[pId + 1] === '*' ?
                match(sId, pId + 2) :
                false;
        }
        return container[`${sId}:${pId}`];
    };

    return match(0, 0);
};
// @lc code=end