You are given a string num representing a large integer. A ‘good’ integer is defined as a substring of length 3, consisting of only one unique digit. Your task is to find the largest ‘good’ integer in the string. If no such integer exists, return an empty string.
Alice is texting Bob using her phone’s keypad. Each digit from ‘2’ to ‘9’ maps to multiple letters, and Alice has to press a key several times to type each letter. However, due to a transmission error, Bob receives a string of digits corresponding to the number of key presses rather than the message itself. Your task is to determine how many possible messages Alice could have sent, given the sequence of digits Bob received. The answer should be returned modulo 1e9 + 7.
The k-beauty of a number is defined as the number of contiguous substrings of length k that are divisors of the original number when it is read as a string. Your task is to determine the k-beauty of a given number num.
You are given a 0-indexed string array words, where each element of words[i] consists of lowercase English letters. In one operation, you can delete any word words[i] if it is an anagram of the previous word words[i-1]. Repeat this operation until no more deletions are possible. Your task is to return the list of words after performing all possible operations.
You are given a string s and a character letter. Your task is to determine the percentage of characters in s that are equal to letter, rounding down to the nearest whole percent.
You are given a string num consisting of digits, where each digit represents a specific number. The task is to verify if for every index i in the string, the digit at index i appears exactly num[i] times in the entire string. Return true if the condition holds for all indices, and false otherwise.