//

// Implement strStr.swift

//

// Created by PixelShi on 2017/2/11.

// Copyright © 2017年 Krunoslav Zaher. All rights reserved.

//

import Foundation

class Solution {

func strStr(_ haystack: String, _ needle: String) -> Int {

let hChars = Array(haystack.characters)

let nChars = Array(needle.characters)

guard hChars.count >= nChars.count else {

return -1

}

guard nChars.count != 0 else {

return 0

}

for i in 0...(hChars.count - nChars.count) {

// 找到第一个相等的

if hChars[i] == nChars[0] {

for j in 0..<nChars.count {

// 如果子串某一位和父串不相等,退出循环

if hChars[i+j] != nChars[j] {

break

}

// 找到子串匹配父串

if j + 1 == nChars.count {

return i

}

}

}

}

return -1

}

}