Hashmap

Problem On our special chessboard, two bishops attack each other if they share the same diagonal. This includes bishops that have another bishop located between them, i.e. bishops can attack through pieces. You are given N bishops, represented as (row, column) tuples on an M by M chessboard. Write a function to count the number of pairs of bishops that attack each other. The ordering of the pair doesn’t matter: (1, 2) is considered the same as (2, 1). ...

Problem You are given a 0-indexed integer array mapping which represents the mapping rule of a shuffled decimal system. mapping[i] = j means digit i should be mapped to digit j in this system. The mapped value of an integer is the new integer obtained by replacing each occurrence of digit i in the integer with mapping[i] for all 0 <= i <= 9. You are also given another integer array nums. Return the array nums sorted in non-decreasing order based on the mapped values of its elements. ...

Problem Design and implement a data structure for Least Recently Used (LRU) cache. It should support the following operations: get and add. Implement the LRUCache class: LRUCache(int capacity) Initialize the LRU cache with positive size capacity. int get(int key) Return the value of the key if the key exists, otherwise return -1. void put(int key, int value) Update the value of the key if the key exists. Otherwise, add the key-value pair to the cache. If the number of keys exceeds the capacity from this operation, evict the least recently used key. The functions get and put must each run in O(1) average time complexity. ...

Problem Given a pattern and a string s, find if s follows the same pattern. Here follow means a full match, such that there is a bijection between a letter in pattern and a non-empty word in s. Examples Example 1: Input: pattern = "abba", s = "dog cat cat dog" Output: true Example 2: ...

Problem Given a string text, you want to use the characters of text to form as many instances of the word “balloon” as possible. You can use each character in text at most once. Return the maximum number of instances that can be formed. Examples Example 1: Input: text = "nlaebolko" Output: 1 Example 2: Input: text = "loonbalxballpoon" Output: 2 ...