Скачать или смотреть Leetcode C++ Length of the Longest Valid Substring - Interview Question

Leetcode problem 2781. Length of the Longest Valid Substring.

The way to solve this is to iterate from right to left of the word while checking a hash (unordered_set) for forbidden words. The coder needs to maintain a right wall. A needed optimization is not checking when the window size is greater than the maximum forbidden word size.

This is a question frequently asked during coding interviews.


Question:

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 11 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 less than or equal word.length less than or equal 105
word consists only of lowercase English letters.
1 less than or equal forbidden.length less than or equal 105
1 less than or equal forbidden[i].length less than or equal 10
forbidden[i] consists only of lowercase English letters.