For a non-negative integer X, the array-form of X is an array of its digits in left to right order. For example, if X = 1231, then the array form is [1,2,3,1].Given the array-form A of a non-negative integer X, return the array-form of the integer X+K.Example 1:

Given a column title as appear in an Excel sheet, return its corresponding column number.For example:

Given an array A of strings made only from lowercase letters, return a list of all characters that show up in all strings within the list (including duplicates). For example, if a character occurs 3 times in all strings but not 4 times, you need to include that character three times in the final ...

Given two strings A and B of lowercase letters, return true if and only if we can swap two letters in A so that the result equals B.

Given a string, you need to reverse the order of characters in each word within a sentence while still preserving whitespace and initial word order.

Given a string, find the first non-repeating character in it and return it's index. If it doesn't exist, return -1.

Given a positive integer n, find the least number of perfect square numbers (for example, 1, 4, 9, 16, ...) which sum to n.

You are given coins of different denominations and a total amount of money amount. Write a function to compute the fewest number of coins that you need to make up that amount. If that amount of money cannot be made up by any combination of the coins, return -1.

Given a string array words, find the maximum value of length(word[i]) * length(word[j]) where the two words do not share common letters. You may assume that each word will contain only lower case letters. If no such two words exist, return 0.

Write a program to find the nth super ugly number.Super ugly numbers are positive numbers whose all prime factors are in the given prime list primes of size k.

Given an Iterator class interface with methods: next() and hasNext(), design and implement a PeekingIterator that support the peek() operation -- it essentially peek() at the element that will be returned by the next call to next().

Count the number of prime numbers less than a non-negative number, n. Example: {代码...} 难度：easy 题目：统计小于非负整数n的所有素数。 思路：参考素数筛选法。 Runtime: 11 ms, faster than 94.69% of Java online submissions for Count Primes.Memory Usage: 35.9 MB, less than 21.43% of Java online subm...

Given an array of citations sorted in ascending order (each citation is a non-negative integer) of a researcher, write a function to compute the researcher's h-index.

Given an array of citations (each citation is a non-negative integer) of a researcher, write a function to compute the researcher's h-index.

Ugly numbers are positive numbers whose prime factors only include 2, 3, 5.

Given a string of numbers and operators, return all possible results from computing all the different possible ways to group numbers and operators. The valid operators are +, - and *.

Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties:Integers in each row are sorted in ascending from left to right.Integers in each column are sorted in ascending from top to bottom.Example:

Given an array nums of n integers where n > 1, return an array output such that output[i] is equal to the product of all the elements of nums except nums[i].Example:

Given an integer array of size n, find all elements that appear more than ⌊ n/3 ⌋ times.Note: The algorithm should run in linear time and in O(1) space.Example 1:

Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree.

You are playing the following Bulls and Cows game with your friend: You write down a number and ask your friend to guess what the number is. Each time your friend makes a guess, you provide a hint that indicates how many digits in said guess match your secret number exactly in both digit and posi...

Given an unsorted array of integers, find the length of longest increasing subsequence.Example:

Given a 2D matrix matrix, find the sum of the elements inside the rectangle defined by its upper left corner (row1, col1) and lower right corner (row2, col2).

Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST.For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more than 1.Example:

Given a binary search tree, write a function kthSmallest to find the kth smallest element in it.Note: You may assume k is always valid, 1 ≤ k ≤ BST's total elements.Example 1:

Given a sorted integer array without duplicates, return the summary of its ranges.Example 1:

In an array A containing only 0s and 1s, a K-bit flip consists of choosing a (contiguous) subarray of length K and simultaneously changing every 0 in the subarray to 1, and every 1 in the subarray to 0.

Given the head of a graph, return a deep copy (clone) of the graph. Each node in the graph contains a label (int) and a list (List[UndirectedGraphNode]) of its neighbors. There is an edge between the given node and each of the nodes in its neighbors.

Given inorder and postorder traversal of a tree, construct the binary tree.Note:You may assume that duplicates do not exist in the tree.For example, given

Given preorder and inorder traversal of a tree, construct the binary tree.Note:You may assume that duplicates do not exist in the tree.For example, given