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438. Find All Anagrams in a String Given two strings s and p, return an array of all the start indices of p’s anagrams in s. You may return the answer in any order. Example 1: Input: s = "cbaebabacd", p = "abc" Output: [0,6] Explanation: The substring with start index = 0 is "cba", which is an anagram of "abc". The substring with start index = 6 is "bac", which is an anagram of "abc". Example 2: Input: s = "abab", p = "ab" Output: [0,1,2] Explanation: The substring with start index = 0 is "ab", which is an anagram of "ab". The substring with start index = 1 is "ba", which is an anagram of "ab". The substring with start index = 2 is "ab", which is an anagram of "ab". Constraints: ...

1208. Get Equal Substrings Within Budget You are given two strings s and t of the same length. You want to change s to t. Changing the i-th character of s to i-th character of t costs |s[i] - t[i]| that is, the absolute difference between the ASCII values of the characters. You are also given an integer maxCost. Return the maximum length of a substring of s that can be changed to be the same as the corresponding substring of twith a cost less than or equal to maxCost. ...

443. String Compression Given an array of characters chars, compress it using the following algorithm: Begin with an empty string s. For each group of consecutive repeating characters in chars: If the group’s length is 1, append the character to s. Otherwise, append the character followed by the group’s length. The compressed string s should not be returned separately, but instead be stored in the input character array chars. Note that group lengths that are 10 or longer will be split into multiple characters in chars. ...

1207. Unique Number of Occurrences Given an array of integers arr, write a function that returns true if and only if the number of occurrences of each value in the array is unique. Example 1: Input: arr = [1,2,2,1,1,3] Output: true Explanation: The value 1 has 3 occurrences, 2 has 2 and 3 has 1. No two values have the same number of occurrences. Example 2: Input: arr = [1,2] Output: false Example 3: Input: arr = [-3,0,1,-3,1,1,1,-3,10,0] Output: true Constraints: ...

1455. Check If a Word Occurs As a Prefix of Any Word in a Sentence Given a sentence that consists of some words separated by a single space, and a searchWord. You have to check if searchWord is a prefix of any word in sentence. Return the index of the word in sentence where searchWord is a prefix of this word (1-indexed). If searchWord is a prefix of more than one word, return the index of the first word (minimum index). If there is no such word return -1. ...

1844. Replace All Digits with Characters You are given a 0-indexed string s that has lowercase English letters in its even indices and digits in its odd indices. There is a function shift(c, x), where c is a character and x is a digit, that returns the xth character after c. For example, shift(‘a’, 5) = ‘f’ and shift(‘x’, 0) = ‘x’. For every odd index i, you want to replace the digit s[i] with shift(s[i-1], s[i]). ...

859. Buddy Strings Given two strings a and b, return true if you can swap two letters in a so the result is equal to b, otherwise, return false. Swapping letters is defined as taking two indices i and j (0-indexed) such that i != j and swapping the characters at a[i] and a[j]. For example, swapping at indices 0 and 2 in “abcd” results in “cbad”. Example 1: Input: a = "ab", b = "ba" Output: true Explanation: You can swap a[0] = 'a' and a[1] = 'b' to get "ba", which is equal to b. Example 2: Input: a = "ab", b = "ab" Output: false Explanation: The only letters you can swap are a[0] = 'a' and a[1] = 'b', which results in "ba" != b. Example 3: Input: a = "aa", b = "aa" Output: true Explanation: You can swap a[0] = 'a' and a[1] = 'a' to get "aa", which is equal to b. Example 4: Input: a = "aaaaaaabc", b = "aaaaaaacb" Output: true Constraints: ...

211. Design Add and Search Words Data Structure Design a data structure that supports adding new words and finding if a string matches any previously added string. Implement the WordDictionary class: WordDictionary() Initializes the object. void addWord(word) Adds word to the data structure, it can be matched later. bool search(word) Returns true if there is any string in the data structure that - matches word or false otherwise. word may contain dots ‘.’ where dots can be matched with any letter. Example: Input ["WordDictionary","addWord","addWord","addWord","search","search","search","search"] [[],["bad"],["dad"],["mad"],["pad"],["bad"],[".ad"],["b.."]] Output [null,null,null,null,false,true,true,true] Explanation WordDictionary wordDictionary = new WordDictionary(); wordDictionary.addWord("bad"); wordDictionary.addWord("dad"); wordDictionary.addWord("mad"); wordDictionary.search("pad"); // return False wordDictionary.search("bad"); // return True wordDictionary.search(".ad"); // return True wordDictionary.search("b.."); // return True Constraints: ...

72. Edit Distance Given two strings word1 and word2, return the minimum number of operations required to convert word1 to word2. You have the following three operations permitted on a word: Insert a character Delete a character Replace a character Example 1: Input: word1 = "horse", word2 = "ros" Output: 3 Explanation: horse -> rorse (replace 'h' with 'r') rorse -> rose (remove 'r') rose -> ros (remove 'e') Example 2: Input: word1 = "intention", word2 = "execution" Output: 5 Explanation: intention -> inention (remove 't') inention -> enention (replace 'i' with 'e') enention -> exention (replace 'n' with 'x') exention -> exection (replace 'n' with 'c') exection -> execution (insert 'u') Constraints: ...

720. Longest Word in Dictionary Given an array of strings words representing an English Dictionary, return the longest word in words that can be built one character at a time by other words in words. If there is more than one possible answer, return the longest word with the smallest lexicographical order. If there is no answer, return the empty string. Example 1: Input: words = ["w","wo","wor","worl","world"] Output: "world" Explanation: The word "world" can be built one character at a time by "w", "wo", "wor", and "worl". Example 2: Input: words = ["a","banana","app","appl","ap","apply","apple"] Output: "apple" Explanation: Both "apply" and "apple" can be built from other words in the dictionary. However, "apple" is lexicographically smaller than "apply". Constraints: ...