18PermutationInString.swift

//
//  ViewController.swift
//  
//
//  Created by thailinh on 5/19/20.
//  Copyright © 2020 thailinh. All rights reserved.
//

import UIKit

class Solution {
    func checkInclusion(_ s1: String, _ s2: String) -> Bool {
        var results = [Int]()
        let p = s1
        let s = s2
        let lengthOfP = p.count
        let lengthOfS = s.count
     
        
        if(lengthOfS==0||lengthOfS<lengthOfP){return false}
        
        let newS = s.map { Int($0.asciiValue! - 97) }
        let newP = p.map { Int($0.asciiValue! - 97) }
        
        var markCharactersOfP = Array(repeating: 0, count: 26)
        var markCharactersOfS = Array(repeating: 0, count: 26)
        
        for index in 0..<p.count {
            markCharactersOfP[newP[index]] += 1
            
            markCharactersOfS[newS[index]] += 1
        }
        
        if compareArray(left: markCharactersOfS, right: markCharactersOfP){
            return true
        }

        for index in (lengthOfP)..<lengthOfS{
            
            markCharactersOfS[newS[index]] += 1
            markCharactersOfS[newS[index - lengthOfP]] -= 1

            if compareArray(left: markCharactersOfS, right: markCharactersOfP){
                return true
            }
        }
        
        return false
    }
    func compareArray (left : [Int], right :  [Int]) -> Bool {
        // left count == right count
        for index in 0..<left.count{
            if left[index] != right[index]{
                return false
            }
        }
        return true
    }

}