3. Longest Substring Without Repeating Characters

1. Sliding window

class Solution(object):
    def lengthOfLongestSubstring(self, s):
        """
        :type s: str
        :rtype: int
        """
        if len(s) <= 1:
            return len(s)
        l = r = 0
        max_length = 1
        mp = []
        for i in range(len(s)):
            r = i
            if s[i] in mp:
                for j in range(l, r):
                    if s[j] == s[i]:
                        l = j + 1
                        break
            else:
                mp.append(s[i])
            max_length = max(r - l + 1, max_length)
        return max_length

func lengthOfLongestSubstring(s string) int {
    if len(s) <= 1 { return len(s) }
    var l int = 0
    var r int = 0
    var size int = len(s)
    var longest int = 1
    var appeared []byte
    for i := 0; i < size; i++ {
        r = i
        if isValueInList(appeared, s[i]) {
            for j := l; j < r; j++ {
                if s[j] == s[i]{
                    l = j + 1
                    break
                }
            }
        } else {
            appeared = append(appeared, s[i])
        }
        if (r - l + 1 > longest){
            longest = r - l + 1
        }
    }
    return longest
}
func isValueInList(list []byte, val byte) bool {
    for _, v := range list {
        if v == val{
            return true
        }
    } 
    return false
}