LRU Cache Design and implement a data structure for Least Recently Used (LRU) cache. It should support the following operations: get and set. get(key) – Get the value (will always be positive) of the key if the key exists in the cache, otherwise return -1. set(key, value) – Set or […]
Median of Two Sorted Arrays There are two sorted arrays A and B of size m and n respectively. Find the median of the two sorted arrays. The overall run time complexity should be O(log (m+n)). tag: divide and conquer, array, binary search 9/22/2015 update Rewrite it in c++ version. […]
Palindrome Number Determine whether an integer is a palindrome. Do this without extra space. Some hints: Could negative integers be palindromes? (ie, -1) If you are thinking of converting the integer to string, note the restriction of using extra space. You could also try reversing an integer. However, if you […]
Candy There are N children standing in a line. Each child is assigned a rating value. You are giving candies to these children subjected to the following requirements: Each child must have at least one candy. Children with a higher rating get more candies than their neighbors. What is the […]
Evaluate Reverse Polish Notation Evaluate the value of an arithmetic expression in Reverse Polish Notation. Valid operators are +, -, *, /. Each operand may be an integer or another expression. Some examples: [“2”, “1”, “+”, “3”, “*”] -> ((2 + 1) * 3) -> 9 [“4”, “13”, “5”, “/”, […]
Count and Say The count-and-say sequence is the sequence of integers beginning as follows: 1, 11, 21, 1211, 111221, … 1 is read off as “one 1” or 11. 11 is read off as “two 1s” or 21. 21 is read off as “one 2, then one 1” or 1211. […]
Letter Combinations of a Phone Number Given a digit string, return all possible letter combinations that the number could represent. A mapping of digit to letters (just like on the telephone buttons) is given below. Input:Digit string “23” Output: [“ad”, “ae”, “af”, “bd”, “be”, “bf”, “cd”, “ce”, “cf”]. Note: Although […]
Remove Duplicates from Sorted List Given a sorted linked list, delete all duplicates such that each element appear only once. For example, Given 1->1->2, return 1->2. Given 1->1->2->3->3, return 1->2->3. tag: linked list 简单题，但要注意两点： 1. if 语句条件的判断顺序为从左到右，所以要把判断P为空放在左面先判断，然后再判断p->val == head->val 2. 在函数开始时，把head拷贝给re作为返回元素，head在操作中会被移动。当然，另一个好习惯是把head拷贝成p，然后操作p，最后返回head。 /** * Definition for singly-linked list. * struct ListNode […]
Excel Sheet Column Title Given a positive integer, return its corresponding column title as appear in an Excel sheet. For example: 1 -> A 2 -> B 3 -> C … 26 -> Z 27 -> AA 28 -> AB Credits: Special thanks to @ifanchu for adding this problem and […]
Regular Expression Matching Implement regular expression matching with support for ‘.’ and ‘*’. ‘.’ Matches any single character. ‘*’ Matches zero or more of the preceding element. The matching should cover the entire input string (not partial). The function prototype should be: bool isMatch(const char *s, const char *p) Some […]
