songxt

描述：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 *.

描述：Given a binary tree, return the level order traversal of its nodes’ values. (ie, from left to right, level by level).For example: Given binary tree [3,9,20,null,null,15,7], 3 / \ 9 20 /

描述：Given a binary tree, return the bottom-up level order traversal of its nodes’ values. (ie, from left to right, level by level from leaf to root).For example: Given binary tree [3,9,20,null,null,15

描述：You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return

描述：Given a string, your task is to count how many palindromic substrings in this string.The substrings with different start indexes or end indexes are counted as different substrings even they consist

描述：Given a non negative integer number num. For every numbers i in the range 0 ≤ i ≤ num calculate the number of 1’s in their binary representation and return them as an array.Example: For num = 5 yo

描述：Given an encoded string, return it’s decoded string.The encoding rule is: k[encoded_string], where the encoded_string inside the square brackets is being repeated exactly k times. Note that k is gu

描述：A robot is located at the top-left corner of a m x n grid (marked ‘Start’ in the diagram below).The robot can only move either down or right at any point in time. The robot is trying to reach the b

描述：Follow up for “Unique Paths”:Now consider if some obstacles are added to the grids. How many unique paths would there be?An obstacle and empty space is marked as 1 and 0 respectively in the grid.

描述：Given a positive integer n, break it into the sum of at least two positive integers and maximize the product of those integers. Return the maximum product you can get.For example, given n = 2, retu

描述：Given two strings s1, s2, find the lowest ASCII sum of deleted characters to make two strings equal.Example 1: Input: s1 = “sea”, s2 = “eat” Output: 231 Explanation: Deleting “s” from “sea”

题目：8.3 STINGY SAT is the following problem: given a set of clauses (each a disjunction of literals) and an integer k, find a satisfying assignment in which at most k variables are true, if such an assi

描述：On a staircase, the i-th step has some non-negative cost cost[i] assigned (0 indexed).Once you pay the cost, you can either climb one or two steps. You need to find minimum cost to reach the top of

描述：You are climbing a stair case. It takes n steps to reach to the top.Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?Note: Given n will be a positive

描述：You need to find the largest value in each row of a binary tree. Example: Input: 1 / \ 3 2 / \ \ 5 3 9 Output: [1, 3, 9]分析：这道题要求找到每层树中最大的元素，并输出。思路一：用bfs对整棵数进行搜索

描述：Implement a magic directory with buildDict, and search methods.For the method buildDict, you’ll be given a list of non-repetitive words to build a dictionary.For the method search, you’ll be given

描述：Given an array of integers, return indices of the two numbers such that they add up to a specific target.You may assume that each input would have exactly one solution, and you may not use the same

描述：Given a binary tree, find its maximum depth.The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.树的结构： /** Definition for a binar

描述：Given a List of words, return the words that can be typed using letters of alphabet on only one row’s of American keyboard like the image below. Example 1: Input: [“Hello”, “Alaska”, “Dad”, “Peace

描述：Given two binary trees, write a function to check if they are equal or not.Two binary trees are considered equal if they are structurally identical and the nodes have the same value.分析：判断两棵树是否相等，水

描述：Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.For example: Given the below binary tree and sum

描述：Given a binary tree and a sum, find all root-to-leaf paths where each path’s sum equals the given sum.For example: Given the below binary tree and sum = 22, 5 / \ 4 8

描述：Given an array of size n, find the majority element. The majority element is the element that appears more than ⌊ n/2 ⌋ times.You may assume that the array is non-empty and the majority element alw

描述：Find the kth largest element in an unsorted array. Note that it is the kth largest element in the sorted order, not the kth distinct element.Example, Given [3,2,1,5,6,4] and k = 2, return 5. Note

描述：Find the contiguous subarray within an array (containing at least one number) which has the largest sum.For example, given the array [-2,1,-3,4,-1,2,1,-5,4], the contiguous subarray [4,-1,2,1] has

描述：Given four lists A, B, C, D of integer values, compute how many tuples (i, j, k, l) there are such that A[i] + B[j] + C[k] + D[l] is zero.To make problem a bit easier, all A, B, C, D have same leng

描述：Given two arrays, write a function to compute their intersection.Example: Given nums1 = [1, 2, 2, 1], nums2 = [2, 2], return [2].Note: Each element in the result must be unique. The result can b

描述：Given two arrays, write a function to compute their intersection.Example: Given nums1 = [1, 2, 2, 1], nums2 = [2, 2], return [2, 2].Note: Each element in the result should appear as many times as

描述：You are given a data structure of employee information, which includes the employee’s unique id, his importance value and his direct subordinates’ id.For example, employee 1 is the leader of employ

描述：Given a binary tree, find the leftmost value in the last row of the tree. Example 1: Input: 2 / \ 1 3Output: 1

描述：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 i