LeetCode in Kotlin
3. Longest Substring Without Repeating Characters
Medium
Given a string s, find the length of the longest substring without repeating characters.
Example 1:
Input: s = “abcabcbb”
Output: 3
Explanation: The answer is “abc”, with the length of 3.
Example 2:
Input: s = “bbbbb”
Output: 1
Explanation: The answer is “b”, with the length of 1.
Example 3:
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.
Example 4:
Input: s = “”
Output: 0
Constraints:
0 <= s.length <= 5 * 104sconsists of English letters, digits, symbols and spaces.
Solution
class Solution {
fun lengthOfLongestSubstring(s: String): Int {
var i = 0
var j = 0
var longest = 0
// 1. if string empty, return 0
if (s.isEmpty()) {
return 0
}
while (j < s.length) {
// 2. if the char at index j already seen, update the longest if needs
if (i != j && s.substring(i, j).indexOf(s[j]) > -1) {
longest = Math.max(j - i, longest)
i++
} else {
// 3. j out of bound already, update longest
if (++j == s.length) {
longest = Math.max(s.length - i, longest)
break
}
}
}
return longest
}
}