longestchar.go

// Source: https://leetcode.com/problems/longest-substring-without-repeating-characters/
// Author: Lin Tanghui
// Date  : 2015/10/31

// Given a string, find the length of the longest substring without repeating characters.
// For example, the longest substring without repeating letters
// for "abcabcbb" is "abc", which the length is 3.
// For "bbbbb" the longest substring is "b", with the length of 1.

package lenthofsubstring

func lengthOfLongestSubstring(s string) int {
    if s == "" {
        return 0
    }
    var (
        substring       map[rune]int = make(map[rune]int, 0)
        m, longest, num int
    )
    for index, ch := range s {
        num, _ = substring[ch]
        m = max(num, m)
        substring[ch] = index // update index when has the same num
        longest = max(longest, index-m)
    }
    return longest

}

func max(a, b int) int {
    if a < b {
        return b
    } else {
        return a
    }

}