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

Examples:

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.
給定一個(gè)字符串，返回其最大不重復(fù)長(zhǎng)度。

解法如下(字符重復(fù)時(shí)，重復(fù)位置之前的字符可以不用遍歷 既i=k)：

func lengthOfLongestSubstring(s string) int {
    length := 0
    if len(s) > 0 {
        length = 1
    }
    bs := []byte(s)
    for i := 0; i < len(bs); i++ {
        flag := 0
        for j := i + 1; j < len(bs); j++ {
            for k := i; k < j; k++ {
                if bs[k] == bs[j] {
                    flag = 1
                    break
                }
            }
            if flag > 0 {
                break
            }
            if j-i+1 > length {
                length = j - i + 1
            }
        }
    }
    return length
}