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Nearest common ancestor of binary tree leetcode link 1. Two solutions Recursion - postorder traversal Idea: this problem wants to find the nearest common ancestor of two nodes, so we have to traverse the tree from bottom to top, judge the two children first, and then judge the logic of the root node, so we think of using post order trav ...

Recursive / DFS/BFS In constant update 51. Queen n The n ∧ queen problem studies how to place n ∧ queens in n × N's chessboard, and the Queens can't attack each other. Give you an integer n, which returns the solution of all different ， queen problems. Each solution contains a different chess placement scheme for the n ...

LeetCode best time to buy and sell stocks series summary This kind of dynamic programming is optimized from two-dimensional dynamic gauge to one-dimensional dynamic gauge. Greed can also be used in some problems. catalog: 121 the best time to buy and sell stocks 1 122 the best time to buy and sell stocks 2 123the best time to buy and sell st ...

Local ordering of binary search We already know that binary search is a search algorithm for finding a specific element in an ordered array. What if an array is not globally ordered, but locally ordered? At this time, we can use the divide and conquer strategy. We can perform binary search in the locally ordered interval, and then combine eac ...

preface Give you an array num containing n integers. Judge whether there are three elements a, b and c in num, so that a + b + c = 0? Please find all triples with sum 0 and no repetition. Note: the answer cannot contain repeated ternary 1, Violent solution Seeing that the problem is summed according to conditions, the first thing ...

Suppose a group of people with disordered order stand in a queue, and the array people represents the attributes of some people in the queue (not necessarily in order). Each people[i] = [hi, ki] indicates that the height of the ith person is hi, and there is ki people whose height is greater than or equal to hi in front. Please reconstruct and ...

1. Implement stack with queue graphic Since two queues are used to implement the stack, it must be related to the nature of the queue. It must be changed back and forth. Let's take a look at this process. code implementation typedef struct { Queue* q1; Queue* q2; } MyStack; /** Initialize your data structure here. */ M ...

subject Given an array of words and a length maxWidth, rearrange the words into text with exactly maxWidth characters per line and aligned left and right ends. You should use "greedy algorithm" to place a given word; That is, put as many words in each line as possible. If necessary, it can be filled with space '' so that each line ha ...

Algorithm learning Chapter 1 Palindrome number Difficulty: simple Title: Give you an integer X. if x is a palindrome integer, return true; Otherwise, false is returned. Palindromes are integers whose positive (left to right) and reverse (right to left) reads are the same. For example, 121 is a palindrome, not 123. Idea: First convert an int ...

preface: Hello, everyone. Today is the eighth day of LeetCode's daily question. What I share is the reversal of the linked list and the difficulty coefficient of two stars! No more nonsense, let's start with the topic! 1.1 subject requirements Topic type: linked list inversion Title Content: reverse the link order of the single linked ...