Category: string

Given a string S of lowercase letters, a duplicate removal consists of choosing two adjacent and equal letters, and removing them. We repeatedly make duplicate removals on S until …

Implement strStr(). Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack. Example 1: Input: haystack = “hello”, needle …

Given a non-empty string s and an abbreviation abbr, return whether the string matches with the given abbreviation. A string such as “word” contains only the following valid abbreviations: …

In an alien language, surprisingly they also use english lowercase letters, but possibly in a different order. The order of the alphabet is some permutation of lowercase letters. Given …

A valid parentheses string is either empty (“”), “(” + A + “)”, or A + B, where A and B are valid parentheses strings, and + represents string …