dldldl1994的博客

题目：Given an integer n, generate all structurally unique BST’s (binary search trees) that store values 1 … n.Example:Input: 3Output:[[1,null,3,2],[3,2,null,1],[3,1,null,null,2],[2,1,3],[1,nul...

题目：Given n, how many structurally unique BST’s (binary search trees) that store values 1 … n?Example:Input: 3Output: 5Explanation:Given n = 3, there are a total of 5 unique BST’s:1 3 ...

题目：The gray code is a binary numeral system where two successive values differ in only one bit.Given a non-negative integer n representing the total number of bits in the code, print the sequence of...

题目：Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array.Note:The number of elements initialized in nums1 and nums2 are m and n respectively.You may assume th...

题目：Given a linked list and a value x, partition it such that all nodes less than x come before nodes greater than or equal to x.You should preserve the original relative order of the nodes in each o...

题目：Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.Example 1:Input: 1->2->3->3->4->4->5Output: 1-&g...

题目：Given a sorted linked list, delete all duplicates such that each element appear only once.Example 1:Input: 1->1->2Output: 1->2Example 2:Input: 1->1->2->3->3Output: 1-&gt...

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 become [2,5,6,0,0,1,2]).You are given a target value to search. If foun...

题目：Given a sorted array nums, remove the duplicates in-place such that duplicates appeared at most twice and return the new length.Do not allocate extra space for another array, you must do this by ...

题目：Given a linked list, rotate the list to the right by k places, where k is non-negative.Example 1:Input: 1->2->3->4->5->NULL, k = 2Output: 4->5->1->2->3->NULLExpla...

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 duplicate subsets.Example:Input: [1,2,2]...

题目：Given a set of distinct integers, nums, return all possible subsets (the power set).Note: The solution set must not contain duplicate subsets.Example:Input: nums = [1,2,3]Output:[[3],[1],[...

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” cells are those horizontally or verticall...

题目：Given two integers n and k, return all possible combinations of k numbers out of 1 … n.Example:Input: n = 4, k = 2Output:[[2,4],[3,4],[2,3],[1,2],[1,3],[1,4],]解法1：递归法c++：class Solut...

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 order red, white and blue.Here, we will use the...

题目：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 from left to right.The first integer of each r...

题目：Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in-place.Example 1:Input:[[1,1,1],[1,0,1],[1,1,1]]Output:[[1,0,1],[0,0,0],[1,0,1]]Example 2:Input...

题目：Given an absolute path for a file (Unix-style), simplify it. Or in other words, convert it to the canonical path.In a UNIX-style file system, a period . refers to the current directory. Furthermo...

题目：Given a non-empty array of digits representing a non-negative integer, plus one to the integer.The digits are stored such that the most significant digit is at the head of the list, and each elem...

题目：Given two binary strings, return their sum (also a binary string).The input strings are both non-empty and contains only characters 1 or 0.Example 1:Input: a = “11”, b = “1”Output: “100”Examp...

题目：Implement int sqrt(int x).Compute and return the square root of x, where x is guaranteed to be a non-negative integer.Since the return type is an integer, the decimal digits are truncated and on...

题目：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 positi...

题目：The set [1,2,3,…,n] contains a total of n! unique permutations.By listing and labeling all of the permutations in order, we get the following sequence for n = 3:“123”“132”“213”“231”“312”“32...

题目：Given a collection of intervals, merge all overlapping intervals.Example 1:Input: [[1,3],[2,6],[8,10],[15,18]]Output: [[1,6],[8,10],[15,18]]Explanation: Since intervals [1,3] and [2,6] overlap...

题目：Given two non-negative integers num1 and num2 represented as strings, return the product of num1 and num2, also represented as a string.Example 1:Input: num1 = “2”, num2 = “3”Output: “6”Exampl...

题目：Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it is able to trap after raining.The above elevation map is represented by ar...

题目：Given an input string (s) and a pattern §, implement wildcard pattern matching with support for ‘?’ and ‘*’.‘?’ Matches any single character.‘*’ Matches any sequence of characters (including the...

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 jump length at that position.Your goal is ...

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 jump length at that position.Determine if ...

题目：Given a collection of distinct integers, return all possible permutations.Example:Input: [1,2,3]Output:[[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]求全排列，没有重复的元素解法1：调用函数...

题目：Given a collection of numbers that might contain duplicates, return all possible unique permutations.Example:Input: [1,1,2]Output:[[1,1,2],[1,2,1],[2,1,1]]这次有重复需要去重，46题的解法1和解法2无需修改仍可使用解法...

题目：You are given an n x n 2D matrix representing an image.Rotate the image by 90 degrees (clockwise).Note:You have to rotate the image in-place, which means you have to modify the input 2D matrix ...

题目：Given an array of strings, group anagrams together.Example:Input: [“eat”, “tea”, “tan”, “ate”, “nat”, “bat”],Output:[[“ate”,“eat”,“tea”],[“nat”,“tan”],[“bat”]]Note:All inputs will be in ...

题目：Implement pow(x, n), which calculates x raised to the power n (xn).Example 1:Input: 2.00000, 10Output: 1024.00000Example 2:Input: 2.10000, 3Output: 9.26100Example 3:Input: 2.00000, -2Outp...

题目：The 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 the number of distinct solutions to the n-queens ...

题目：The 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 n-queens puzzle.Ea...

题目：53. Maximum SubarrayGiven an integer array nums, find the contiguous subarray (containing at least one number) which has the largest sum and return its sum.Example:Input: [-2,1,-3,4,-1,2,1,-5,4...

题目：Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.Example 1:Input:[[ 1, 2, 3 ],[ 4, 5, 6 ],[ 7, 8, 9 ]]Output: [1,2,3,6,9,8,7,4,5]Exa...

题目：Given a positive integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.Example:Input: 3Output:[[ 1, 2, 3 ],[ 8, 9, 4 ],[ 7, 6, 5 ]]此题与

题目：Given a string s consists of upper/lower-case alphabets and empty space characters ’ ', return the length of last word in the string.If the last word does not exist, return 0.Note: A word is def...