Ethan95的博客

地址：https://leetcode.com/problems/spiral-matrix/题目：Given a matrix of mxnm x nmxn elements (mmm rows, nnn columns), return all elements of the matrix in spiral order.Example 1:Example 2:理解：按规则走一...

地址：https://leetcode.com/problems/unique-paths-ii/题目：A robot is located at the top-left corner of a m∗nm * nm∗n grid (marked ‘Start’ in the diagram below).The robot can only move either down or righ...

地址：https://leetcode.com/problems/minimum-path-sum/题目：Given a m∗nm * nm∗n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all numbers along...

地址：https://leetcode.com/problems/search-in-rotated-sorted-array-ii/题目：Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand.(i.e., [0,0,1,2,2,5,6] might beco...

地址：https://leetcode.com/problems/reverse-linked-list-ii/题目：Reverse a linked list from position m to n. Do it in one-pass.Note: 1 ≤ m ≤ n ≤ length of list.Example:Input: 1->2->3->4->5...

地址：https://leetcode.com/problems/restore-ip-addresses/题目：Given a string containing only digits, restore it by returning all possible valid IP address combinations.Example:Input: “25525511135”Out...

地址：https://leetcode.com/problems/combinations/题目：Given two integers n and k, return all possible combinations of k numbers out of 1 … n.Example:理解：很像前面的permutation还有combinatio sum的问题，用backtracki...

地址：https://leetcode.com/problems/subsets/题目：Given a set of distinct integers, numsnumsnums, return all possible subsets (the power set).Note: The solution set must not contain duplicate subsets.Ex...

地址：https://leetcode.com/problems/remove-duplicates-from-sorted-list-ii/题目：Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original li...

地址：https://leetcode.com/problems/sort-colors/题目：Given an array with n objects colored red, white or blue, sort them in-place so that objects of the same color are adjacent, with the colors in the or...

地址：https://leetcode.com/problems/search-a-2d-matrix/题目：Write an efficient algorithm that searches for a value in an mmm x nnn matrix. This matrix has the following properties:Integers in each row ...

地址：https://leetcode.com/problems/jump-game/题目：Given an array of non-negative integers, you are initially positioned at the first index of the array.Each element in the array represents your maximum...

地址：https://leetcode.com/problems/jump-game/题目：https://leetcode.com/problems/merge-intervals/Example 1:Example 2:理解：在有序的情况下，直接从头到尾和并一次就可以了。实现：在排序的时候，end的大小其实是不重要的。class Solution {public: v...

地址：https://leetcode.com/problems/rotate-list/题目：Given a linked list, rotate the list to the right by kkk places, where kkk is non-negative.Example 1:Input: 1->2->3->4->5->NULL, k =...

地址：https://leetcode.com/problems/simplify-path/题目：Given an absolute path for a file (Unix-style), simplify it.For example,path = "/home/", => "/home"path = "/a/./b/../../c/", => "/c"path =...

地址：https://leetcode.com/problems/set-matrix-zeroes/题目：Given a mmm x nnn matrix, if an element is 0, set its entire row and column to 0. Do it in-place.Example 1:Example 2:Follow up:A straight...

地址：https://leetcode.com/problems/unique-paths/题目：A robot is located at the top-left corner of a m∗nm * nm∗n grid (marked ‘Start’ in the diagram below).The robot can only move either down or right a...

地址：https://leetcode.com/problems/subsets/题目：Given a 2D board and a word, find if the word exists in the grid.The word can be constructed from letters of sequentially adjacent cell, where “adjacent”...

地址：https://leetcode.com/problems/remove-duplicates-from-sorted-array-ii/题目：Given a sorted array nums, remove the duplicates in-place such that duplicates appeared at most twice and return the new le...

地址：https://leetcode.com/problems/restore-ip-addresses/题目：Given a binary tree, return the inorder traversal of its nodes’ values.Example:理解：二叉树的中序遍历递归实现：class Solution {public: vector<int&...

地址：https://leetcode.com/problems/unique-binary-search-trees/题目：Given nnn, how many structurally unique BST’s (binary search trees) that store values 1...n1 ... n1...n?Example:理解：就是要求n个数的二叉排序树的个数...

地址：https://leetcode.com/problems/partition-list/题目：Given a linked list and a value xxx, partition it such that all nodes less than xxx come before nodes greater than or equal to xxx.You should pres...

地址：https://leetcode.com/problems/jump-game-ii/题目：Given an array of non-negative integers, you are initially positioned at the first index of the array.Each element in the array represents your maxi...

地址：https://leetcode.com/problems/find-all-duplicates-in-an-array/题目：Given an array of integers, 1 ≤ a[i] ≤ nnn (nnn = size of array), some elements appear twice and others appear once.Find all the ...

地址：https://leetcode.com/problems/median-of-two-sorted-arrays/题目：There are two sorted arrays nums1 and nums2 of size m and n respectively.Find the median of the two sorted arrays. The overall run ti...

地址：https://leetcode.com/problems/edit-distance/题目：Given two words word1 and word2, find the minimum number of operations required to convert word1 to word2.You have the following 3 operations permi...

地址：https://leetcode.com/problems/minimum-window-substring/题目：Given 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)O(n)O(n).Exam...

地址：https://leetcode.com/problems/trapping-rain-water/题目：Given nnn non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it is able to trap afte...

地址：https://leetcode.com/problems/largest-rectangle-in-histogram/题目：Given nnn non-negative integers representing the histogram’s bar height where the width of each bar is 1, find the area of largest ...

地址：https://leetcode.com/problems/maximal-rectangle/题目：Given a 2D binary matrix filled with 0’s and 1’s, find the largest rectangle containing only 1’s and return its area.Example:理解：找出给定的矩阵里全1的矩...

地址：https://leetcode.com/problems/count-binary-substrings/题目：Give a string s, count the number of non-empty (contiguous) substrings that have the same number of 0’s and 1’s, and all the 0’s and all t...

地址：https://leetcode.com/problems/longest-valid-parentheses/题目：Given a string containing just the characters '(' and ')', find the length of the longest valid (well-formed) parentheses substring.Exa...

地址：https://leetcode.com/problems/gray-code/题目：The gray code is a binary numeral system where two successive values differ in only one bit.Given a non-negative integer nnn representing the total num...

地址：https://leetcode.com/problems/unique-binary-search-trees-ii/题目：Given an integer nnn, generate all structurally unique BST’s (binary search trees) that store values 111 … nnn.Example:理解：上一道题求的...

地址：https://leetcode.com/problems/validate-binary-search-tree/题目：Given a binary tree, determine if it is a valid binary search tree (BST).Assume a BST is defined as follows:The left subtree of a n...

地址：https://leetcode.com/problems/regular-expression-matching/题目：Given an input string (s) and a pattern (p), implement regular expression matching with support for '.' and '*'.‘.’ Matches any sing...

地址：https://leetcode.com/problems/substring-with-concatenation-of-all-words/题目：You are given a string, s, and a list of words, words, that are all of the same length. Find all starting indices of sub...

地址：https://leetcode.com/problems/gray-code/题目：Given a collection of integers that might contain duplicates, nums, return all possible subsets (the power set).Note: The solution set must not contain...

地址：https://leetcode.com/problems/decode-ways/题目：A message containing letters from A-Z is being encoded to numbers using the following mapping:'A' -> 1'B' -> 2...'Z' -> 26Given a non-e...

地址：https://leetcode.com/problems/merge-k-sorted-lists/题目：Merge kkk sorted linked lists and return it as one sorted list. Analyze and describe its complexity.Example:理解：合并k个有序链表。想到了外部排序里面的败者数，其本质...