Given a string, find the length of the longest substring without repeating characters.

Given "abcabcbb", the answer is "abc", which the length is 3.
Given "bbbbb", the answer is "b", with the length of 1.
Given "pwwkew", the answer is "wke", with the length of 3. Note that the answer must be a substring, "pwke" is a subsequence and not a substring.

答案：(發(fā)現(xiàn)用C刷題好辛苦，還是邊學(xué)Swift邊刷吧)

分析：創(chuàng)建一個(gè) char-int 的hashMap，沒有重復(fù)temMax++，重復(fù)的話，判斷重復(fù)之間有沒有其他的重復(fù)例如 ABCBA，A之間有B重復(fù)，這時(shí)候temMax++就可以了

class Solution {
    func lengthOfLongestSubstring(_ s: String) -> Int {
        let charArr = Array(s.characters);
        let strLen = charArr.count
        if strLen <= 1  {
            return strLen
        }
        var maxLen = 1
        var hashMap = Dictionary<Character,Int>()
        var temMax = 1
        hashMap[charArr[0]] = 0
    
        for i in 1...strLen-1 {
            if let lastPosition = hashMap[charArr[i]] {
                if temMax + lastPosition < i {
                    temMax += 1
                }
                else {
                    temMax = i - lastPosition
                }
            }
            else {
                temMax += 1
            }
            hashMap[charArr[i]] = i
            if temMax > maxLen {
                maxLen = temMax
            }
        }
        return maxLen
    }
}

性能：
時(shí)間復(fù)雜度：O(n)
runtime:179 ms
beats 87.62% submissions