"3. Longest Substring Without Repeating Characters" drastically optimised accepted solution

3-longest-substr-no-repeat-chars.go

@@ -86,6 +86,35 @@ func lengthOfLongestSubstringSlidingWindow(s string) int {
 	return maxChars
 }
 
-func LengthOfLongestSubstring(s string) int {
-	return lengthOfLongestSubstringSlidingWindow(s)
+func lengthOfLongestSubstringExpandingWindow(s string) int {
+	maxChars := 0
+
+	if len(s) == 0 {
+		return 0
+	}
+
+	for i := 0; i < len(s)-maxChars; i++ {
+		charMap := [255]int{}
+		charMapSize := 0
+
+		for j := i; j < len(s); j++ {
+			charMap[s[j]]++
+			if charMap[s[j]] > 1 {
+				break
+			} else {
+				charMapSize++
+			}
+
+		}
+
+		if maxChars < charMapSize {
+			maxChars = charMapSize
+		}
+	}
+
+	return maxChars
+}
+
+func LengthOfLongestSubstring(s string) int {
+	return lengthOfLongestSubstringExpandingWindow(s)
 }