Given a binary tree, we install cameras on the nodes of the tree. Each camera at a node can monitor its parent, itself, and its immediate children. Calculate the minimum number of cameras needed to monitor all nodes of the tree. Example 1: Input: [0,…

二叉树基础 满足这样性质的树称为二叉树:空树或节点最多有两个子树,称为左子树.右子树, 左右子树节点同样最多有两个子树. 二叉树是递归定义的,因而常用递归/DFS的思想处理二叉树相关问题,例如LeetCode题目 104. Maximum Depth of Binary Tree: // 104. Maximum Depth of Binary Tree int maxDepth(TreeNode* root) { ; +max(maxDepth(root->left),maxDepth(roo…

写在前面: 二叉树是比较简单的一种数据结构,理解并熟练掌握其相关算法对于复杂数据结构的学习大有裨益 一.二叉树的创建 [不喜欢理论的点我跳过>>] 所谓的创建二叉树,其实就是让计算机去存储这个特殊的数据结构(特殊在哪里?特殊在它是我们自定义的) 首先,计算机内部存储都是线性的,而我们的树形结构是一种层级的,计算机显然无法理解,计算机能够接受的原始数据类型并不能满足我们的需求 所以,只好自定义一种数据结构来表示层级关系 实际上是要定义结构 + 操作,结构是为操作服务的,举个例子,我们要模拟买票的…

#include <stdio.h> #include <string.h> #include <stdlib.h> #define LIST_INIT_SIZE 10 #define LISTINCREMENT 100 #define STACK_INIT_SIZE 100 #define STACKINCREMENT 10 #define TRUE 1 #define FALSE 0 #define true 1 #define false 0 #define OK…

二叉树(Binary Tree)是最简单的树形数据结构,然而却十分精妙.其衍生出各种算法,以致于占据了数据结构的半壁江山.STL中大名顶顶的关联容器--集合(set).映射(map)便是使用二叉树实现.由于篇幅有限,此处仅作一般介绍(如果想要完全了解二叉树以及其衍生出的各种算法,恐怕要写8~10篇). 1)二叉树(Binary Tree) 顾名思义,就是一个节点分出两个节点,称其为左右子节点:每个子节点又可以分出两个子节点,这样递归分叉,其形状很像一颗倒着的树.二叉树限制了每个节点最多有两个子节…

Given a binary tree, find all leaves and then remove those leaves. Then repeat the previous steps until the tree is empty. Example: Given binary tree 1 / \ 2 3 / \ 4 5 Returns [4, 5, 3], [2], [1]. Explanation: 1. Remove the leaves [4, 5, 3] from the…

One way to serialize a binary tree is to use pre-oder traversal. When we encounter a non-null node, we record the node's value. If it is a null node, we record using a sentinel value such as #. _9_ / \ 3 2 / \ / \ 4 1 # 6 / \ / \ / \ # # # # # # For…

Given a binary tree, return the vertical order traversal of its nodes' values. (ie, from top to bottom, column by column). If two nodes are in the same row and column, the order should be from left to right. Examples: Given binary tree [3,9,20,null,n…

Given a binary tree, find the length of the longest consecutive sequence path. The path refers to any sequence of nodes from some starting node to any node in the tree along the parent-child connections. The longest consecutive path need to be from p…

Serialization is the process of converting a data structure or object into a sequence of bits so that it can be stored in a file or memory buffer, or transmitted across a network connection link to be reconstructed later in the same or another comput…