Given a string
s, find the length of the longest substring without repeating characters.
Input: s = "abcabcbb" Output: 3 Explanation: The answer is "abc", with the length of 3.
Input: s = "bbbbb" Output: 1 Explanation: The answer is "b", with the length of 1.
Input: s = "pwwkew" Output: 3 Explanation: The answer is "wke", with the length of 3. Notice that the answer must be a substring, "pwke" is a subsequence and not a substring.
Input: s = "" Output: 0
0 <= s.length <= 5 * 104
sconsists of English letters, digits, symbols and spaces.
The basic idea of solving this problem is to keep track of all the characters we have already visited and maintain a window size in which each character appeared only once. So throughout the traversal whenever the window size is maximum, that will give us the result.
Time Complexity: O(n) // For traversing all the items in the array.
Space Complexity: O(n) // for keeping track of already visited items in the window, in the worst case all items will be present in the HashSet.