Jin_Kwok的博客

23. Merge k Sorted ListsTotal Accepted: 88102 Total Submissions: 372066 Difficulty: HardMerge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity.

83. Remove Duplicates from Sorted ListTotal Accepted: 111368 Total Submissions: 304182 Difficulty: EasyGiven a sorted linked list, delete all duplicates such that each element appear onl

98. Validate Binary Search TreeTotal Accepted: 90083 Total Submissions: 430775 Difficulty: MediumGiven a binary tree, determine if it is a valid binary search tree (BST).Assume a BST

96. Unique Binary Search TreesTotal Accepted: 80679 Total Submissions: 216054 Difficulty: MediumGiven n, how many structurally unique BST's (binary search trees) that store values 1...n?

80. Remove Duplicates from Sorted Array IITotal Accepted: 71844 Total Submissions: 220521 Difficulty: MediumFollow up for "Remove Duplicates":What if duplicates are allowed at most twi

77. CombinationsTotal Accepted: 72222 Total Submissions: 212130 Difficulty: MediumGiven two integers n and k, return all possible combinations of k numbers out of 1 ... n.For example,

257. Binary Tree PathsMy SubmissionsQuestionTotal Accepted: 40763 Total Submissions: 146109 Difficulty: EasyGiven a binary tree, return all root-to-leaf paths.For example, gi

242. Valid AnagramGiven two strings s and t, write a function to determine if t is an anagram of s.For example,s = "anagram", t = "nagaram", return true.s = "rat", t = "car", return fals

1. Two SumGiven 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.Exampl

【题目】3. Longest Substring Without Repeating CharactersGiven a string, find the length of the longest substring without repeating characters. For example, the longest substring without repeating l

99. Recover Binary Search TreeTotal Accepted: 50739 Total Submissions: 192395 Difficulty: HardTwo elements of a binary search tree (BST) are swapped by mistake.Recover the tree without

101. Symmetric TreeTotal Accepted: 103742 Total Submissions: 306773 Difficulty: EasyGiven a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).For

104. Maximum Depth of Binary TreeTotal Accepted: 137961 Total Submissions: 289093 Difficulty: EasyGiven a binary tree, find its maximum depth.The maximum depth is the number of nodes

113. Path Sum II Total Accepted: 80509 Total Submissions: 284188 Difficulty: MediumGiven a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum.F

347. Top K Frequent ElementsTotal Accepted: 12022 Total Submissions: 28556 Difficulty: MediumGiven a non-empty array of integers, return the k most frequent elements.For example,Gi

215. Kth Largest Element in an ArrayTotal Accepted: 57859 Total Submissions: 171725 Difficulty: MediumFind the kth largest element in an unsorted array. Note that it is the kth largest e

132. Palindrome Partitioning IITotal Accepted: 50256 Total Submissions: 230441 Difficulty: HardGiven a string s, partition s such that every substring of the partition is a palindrome.

120. TriangleTotal Accepted: 69567 Total Submissions: 229977 Difficulty: MediumGiven a triangle, find the minimum path sum from top to bottom. Each step you may move to adjacent numbers

112. Path Sum  Total Accepted: 101647 Total Submissions: 324557 Difficulty: Easy Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all th

111. Minimum Depth of Binary Tree Total Accepted: 104964 Total Submissions: 342426 Difficulty: Easy Given a binary tree, find its minimum depth.The minimum depth is the number of nodes

109. Convert Sorted List to Binary Search Tree  Total Accepted: 68081 Total Submissions: 224585 Difficulty: MediumGiven a singly linked list where elements are sorted in ascending order, con

108. Convert Sorted Array to Binary Search TreeTotal Accepted: 73365 Total Submissions: 197776 Difficulty: MediumGiven an array where elements are sorted in ascending order, convert it to

【题目】【LeetCode】18. 4SumGiven an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of targe

39. Combination SumGiven a set of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T.The same repeated number may

41. First Missing PositiveMy SubmissionsQuestionEditorial SolutionTotal Accepted: 61575 Total Submissions: 259854 Difficulty: HardGiven an unsorted integer array, find th

84. Largest Rectangle in HistogramTotal Accepted: 57808 Total Submissions: 239940 Difficulty: HardGiven n non-negative integers representing the histogram's bar height where the width of

61. Rotate ListGiven a list, rotate the list to the right by k places, where k is non-negative.For example:Given 1->2->3->4->5->NULL and k = 2,return 4->5->1->2->3->NULL.【分析】     这

56. Merge IntervalsGiven a collection of intervals, merge all overlapping intervals.For example,Given [1,3],[2,6],[8,10],[15,18],return [1,6],[8,10],[15,18].【分析】   本题旨在合并区间，给定的区间

53. Maximum SubarrayFind 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 contigu

51. N-QueensThe n-queens puzzle is the problem of placing n queens on an n×n chessboard such that no two queens attack each other.Given an integer n, return all distinct solutions to the

50. Pow(x, n) Total Accepted: 87046 Total Submissions: 312150 Difficulty: MediumImplement pow(x, n).【分析】此题意在实现c++库函数Pow(double x, int n)，即求解x的n次幂。此题的解题思路比较简单：将n次幂“折半”,即：Pow(x,n)=Pow(x,n/2)

49. Group Anagrams Total Accepted: 71543 Total Submissions: 262846 Difficulty: MediumGiven an array of strings, group anagrams together.For example, given: ["eat", "tea", "tan", "ate", "na

48. Rotate ImageYou are given an n x n 2D matrix representing an image.Rotate the image by 90 degrees (clockwise).Follow up:Could you do this in-place?【分析】此题要求将一个二维矩阵旋转90度，官方认证的难度是“Mediu

46. Permutations Given a collection of distinct numbers, return all possible permutations.For example,[1,2,3] have the following permutations:[1,2,3], [1,3,2], [2,1,3], [2,3,1], [3

62. Unique PathsA 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 i

69. Sqrt(x)Implement int sqrt(int x).Compute and return the square root of x.【分析】    对于一个正整数x，我们知道它的平方根不可能超过x/2，因此，基于此思路我们可以遍历[0  x/2]之间的所有正整数，将它们呢的平方与x比较，如果相等或者大于前者小于后者，即找到x的平方根(整数部

70. Climbing StairsYou 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?【分析

31. Next PermutationImplement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers.If such arrangement is not possible, it must rearr

94. Binary Tree Inorder TraversalTotal Accepted: 119866 Total Submissions: 303779 Difficulty: MediumGiven a binary tree, return the inorder traversal of its nodes' values.For example

76. Minimum Window SubstringGiven a string S and a string T, find the minimum window in S which will contain all the characters in T in complexity O(n).For example,S = "ADOBECODEBANC"T