problem Equations are given in the format A / B = k, where A and B are variables represented as strings, and k is a real number (floating point number). Given some queries, return the answers. If the answer does not exist, return -1.0. Exa…

What is Trie tree? Trie tree is a data structure of handling string. - Looking up data in a trie is faster in the worst case O(m)(m is the length of a search string). - There are no collisions of different keys in a trie. - There is no nee…

problem Design an algorithm and write code to find the first common ancestor of two nodes in a binary tree. Avoid storing additional nodes in a data structure. NOTE: This is not necessarily a binary search tree. how to solve Starting from …

problem Given a non-empty string s and a dictionary wordDict containing a list of non-empty words, determine if s can be segmented into a space-separated sequence of one or more dictionary words. You may assume the dictionary does not cont…

problem Given a number of dollars, , and a list of dollar values for distinct coins, , find and print the number of different ways you can make change for dollars if each coin is available in an infinite quantity. how to solve I can solve …

problem Design and implement a data structure for Least Recently Used (LRU) cache. It should support the following operations: get and put. get(key) - Get the value (will always be positive) of the key if the key exists in the cache, other…

problem Problem Statement A palindrome is a string that reads the same forwards and backwards. For example, “abba” and “racecar” are palindromes. An odd palindrome is a palindrome with an odd length. For example, “racecar” is an odd palind…

problem The score of a string is its length multiplied by the number of different characters in the string. For example, the score of “abbcdxc” is 7 * 5 = 35. This is because the length of this string is 7 and there are five different char…

problem Limak is in a casino. He has b dollars. He wants to have at least c dollars (to be able to buy flowers for a girl he likes). In order to achieve that, he must win the money he’s missing. The casino allows guests to risk some of the…

problem What is the difference between a thread and a process? answer English A process can be thought of as an instance of a program in execution. A process is an independent entity to which system resources( cpu time and memory) are allo…

problem You are given a binary tree in which each node contains an integer value(which might be positive or negative). Design an algorithm to count the number of paths that sum to a given value. The path does not need to start or end at th…

problem Given a sorted array of strings that is interspersed with empty strings, write a method to find the location of a given string. how to solve If it were not for the empty strings, we could simply use binary search. With empty string…

problem Given an M * N matrix in which each row and each column is sorted in ascending order, write a method to find an element. how to solve http://articles.leetcode.com/searching-2d-sorted-matrix-part-ii/ The above link is very easy unde…

problem Given a sorted(increasing order) array with unique integer elements, write an algorithm to create a binary search tree with minimal height. How to solve This minimal tree means creating height balanced tree. Firstly, we want the ro…

problem Write a method to sort an array of strings so that all the anagrams are next to each other. how to solve I use hash table. once we have grouped all the words into these lists by anagram. we can then put them back into the array. co…

prblme Write an algorithm to find the "next" node(i.e., in-order successor) of a given node in a binary search tree. (You may assume that each node has a link to its parent or you can get the root node) how to solve "Next" node means that …

problem Given an array of integers, find out whether there are two distinct indices i and j in the array such that the absolute difference between nums[i] and nums[j] is at most t and the absolute difference between i and j is at most k. h…

problem Implement a function to check if a binary tree is a binary search tree. how to solve Binary search tree means that all left nodes must be less than or equal to the current node and all right nodes must be more than or equal to the …

problem Implement a function to check if a binary tree is balanced. how to solve A balanced tree is defined to be a tree such that the heights of the two subtrees of any node never differ by more than one. So I implement a function fetchHe…