LeetCode in Kotlin
2781. Length of the Longest Valid Substring
Hard
You are given a string word and an array of strings forbidden.
A string is called valid if none of its substrings are present in forbidden.
Return the length of the longest valid substring of the string word.
A substring is a contiguous sequence of characters in a string, possibly empty.
Example 1:
Input: word = “cbaaaabc”, forbidden = [“aaa”,”cb”]
Output: 4
Explanation:
There are 9 valid substrings in word: “c”, “b”, “a”, “ba”, “aa”, “bc”, “baa”, “aab”, “ab”, “abc”and “aabc”. The length of the longest valid substring is 4.
It can be shown that all other substrings contain either “aaa” or “cb” as a substring.
Example 2:
Input: word = “leetcode”, forbidden = [“de”,”le”,”e”]
Output: 4
Explanation:
There are 11 valid substrings in word: “l”, “t”, “c”, “o”, “d”, “tc”, “co”, “od”, “tco”, “cod”, and “tcod”. The length of the longest valid substring is 4.
It can be shown that all other substrings contain either “de”, “le”, or “e” as a substring.
Constraints:
1 <= word.length <= 105wordconsists only of lowercase English letters.1 <= forbidden.length <= 1051 <= forbidden[i].length <= 10forbidden[i]consists only of lowercase English letters.
Solution
class Solution {
fun longestValidSubstring(word: String, forbidden: List<String>): Int {
val set = HashSet<String>()
for (s in forbidden) {
set.add(s)
}
val n = word.length
var ans = 0
var i = 0
var j = 0
while (j < n) {
var k = j
while (k > j - 10 && k >= i) {
if (set.contains(word.substring(k, j + 1))) {
i = k + 1
break
}
k--
}
ans = Math.max(j - i + 1, ans)
j++
}
return ans
}
}