ianadiwibowo/central-park

package main

import "fmt"

// 10. Regular Expression Matching (Hard)
// https://leetcode.com/problems/regular-expression-matching/

func isMatch(s string, p string) bool {
    stringIndex := 0
    currentChar := ""

    patternIndex := 0
    charToMatch := ""
    starMode := false
    dotMode := false

    for stringIndex < len(s) || patternIndex < len(p) {
        fmt.Println("\npatternIndex:", patternIndex, "| stringIndex:", stringIndex) // DEBUG

        // Current pattern char
        if patternIndex < len(p) { // If pattern is still available
            if !starMode {
                charToMatch = string(p[patternIndex])
                if patternIndex+1 < len(p) && string(p[patternIndex+1]) == "*" {
                    starMode = true
                }
            }
            fmt.Print("charToMatch: ", charToMatch, " | starMode: ", starMode) // DEBUG

            if charToMatch == "." {
                dotMode = true
            }
            fmt.Println(" | dotMode:", dotMode) // DEBUG
        } else { // If pattern is done but string is still available
            if stringIndex < len(s) {
                return false
            }
        }

        // Current string char
        if stringIndex < len(s) { // If string is still available
            currentChar = string(s[stringIndex])
        } else { // If string is done but pattern is still available
            currentChar = ""
        }
        fmt.Println("currentChar:", currentChar) // DEBUG

        // Compare pattern vs. string char
        if dotMode || currentChar == charToMatch { // Match
            fmt.Println("Match") // DEBUG
            stringIndex += 1     // Advance the string char
            if !starMode {
                patternIndex += 1 // Advance the pattern char by 1 if not star mode
            }
        } else { // Not match
            fmt.Println("Not Match") // DEBUG
            if starMode {
                // if patternIndex+2 >= len(p) {
                //     return false
                // }
                patternIndex += 2 // Advance the pattern char by 2 if star mode
                starMode = false
            } else {
                if patternIndex+1 >= len(p) {
                    return false
                }
                patternIndex += 1 // Advance the pattern char by 1 if not star mode
            }
            dotMode = false
        }
    }

    return true
}