题目如下: Given the following details of a matrix with n columns and 2 rows : The matrix is a binary matrix, which means each element in the matrix can be 0 or 1. The sum of elements of the 0-th(upper) row is given as upper. The sum of elements of the 1-…

[LeetCode]423. Reconstruct Original Digits from English 解题报告(Python) 标签: LeetCode 题目地址:https://leetcode.com/problems/reconstruct-original-digits-from-english/description/ 题目描述: Given a non-empty string containing an out-of-order English representatio…

[LeetCode]109. Convert Sorted List to Binary Search Tree 解题报告(Python) 标签(空格分隔): LeetCode 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.me/ 题目地址:https://leetcode.com/problems/convert-sorted-list-to-binary-search-tree/description/ 题目描述: Given a s…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 目录 题目描述 题目大意 解题方法 后序遍历 相似题目 参考资料 日期 题目地址:https://leetcode.com/problems/reconstruct-itinerary/description/ 题目描述 Given a list of airline tickets represented by pairs of departure and arrival airpo…

题目: Given a list of airline tickets represented by pairs of departure and arrival airports [from, to], reconstruct the itinerary in order. All of the tickets belong to a man who departs from JFK. Thus, the itinerary must begin with JFK. Note: If ther…

Given a non-empty string containing an out-of-order English representation of digits 0-9, output the digits in ascending order. Note: Input contains only lowercase English letters. Input is guaranteed to be valid and can be transformed to its origina…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 目录 题目描述 题目大意 解题方法 方法一:DFS 方法二:BFS 日期 题目地址:https://leetcode.com/submissions/detail/136579829/ 题目描述 Given a non-empty binary tree, return the average value of the nodes on each level in the form o…

题目如下: In an infinite binary tree where every node has two children, the nodes are labelled in row order. In the odd numbered rows (ie., the first, third, fifth,...), the labelling is left to right, while in the even numbered rows (second, fourth, six…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 目录 题目描述 题目大意 解题方法 BFS DFS 日期 题目地址:https://leetcode.com/problems/check-completeness-of-a-binary-tree/ 题目描述 Given a binary tree, determine if it is a complete binary tree. Definition of a complete…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 目录 题目描述 题目大意 解题方法 Java解法 Python解法 日期 题目地址:https://leetcode.com/problems/convert-sorted-array-to-binary-search-tree/#/description 题目描述 Given an array where elements are sorted in ascending order,…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址: https://leetcode.com/problems/longest-increasing-path-in-a-matrix/description/ 题目描述: Given an integer matrix, find the length of the longest increasing path. From each cell, you can either…

1. Description One way to serialize a binary tree is to use pre-order 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 / \ / \ / \…

Problem: Given an array where elements are sorted in ascending order, convert it to a height balanced BST. Solution: 复习一下BST的基本性质:简而言之,对于BST中任意结点x,若其有左右结点 l 或 r ,需满足 l.key ≤ x.key ≤ r.key BST的性能(基本操作耗时)与树高成正比,可改进为较为高效的平衡二叉树,即保持整棵树左右均匀,任意左右子树高度差不大于1 如…

Question: Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST. For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node n…

原题 Given a non-empty binary tree, return the average value of the nodes on each level in the form of an array. Example 1: Input: 3 / 9 20 / 15 7 Output: [3, 14.5, 11] Explanation: The average value of nodes on level 0 is 3, on level 1 is 14.5, and on…

题目如下: Given a binary tree, determine if it is a complete binary tree. Definition of a complete binary tree from Wikipedia:In a complete binary tree every level, except possibly the last, is completely filled, and all nodes in the last level are as fa…

[LeetCode]623. Add One Row to Tree 解题报告(Python) 标签(空格分隔): LeetCode 题目地址:https://leetcode.com/problems/add-one-row-to-tree/description/ 题目描述: Given the root of a binary tree, then value v and depth d, you need to add a row of nodes with value v at the…

Given an index k, return the kth row of the Pascal's triangle. For example, given k = 3, Return [1,3,3,1]. Note: Could you optimize your algorithm to use only O(k) extra space? 思路:最简单的方法就是依照[Leetcode]Pascal's Triangle 的方式自顶向下依次求解,但会造成空间的浪费.若仅仅用一个vect…

[94]Binary Tree Inorder Traversal [95]Unique Binary Search Trees II (2018年11月14日,算法群) 给了一个 n,返回结点是 1 - n 的所有形态的BST. 题解:枚举每个根节点 r, 然后递归的生成左右子树的所有集合,然后做笛卡尔积. /** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * Tr…

[98]Validate Binary Search Tree [99]Recover Binary Search Tree [100]Same Tree [101]Symmetric Tree [104]Maximum Depth of Binary Tree [105]Construct Binary Tree from Preorder and Inorder Traversal [106]Construct Binary Tree from Inorder and Postorder T…

[101]Symmetric Tree 判断一棵树是不是对称. 题解:直接递归判断了,感觉和bfs没有什么强联系,当然如果你一定要用queue改写的话,勉强也能算bfs. // 这个题目的重点是 比较对象是 左子树的左儿子和右子树的右儿子, 左子树的右儿子和右子树的左儿子.不要搞错. // 直接中序遍历的话会有错的情况,最蠢的情况是数字标注改一改.. /** * Definition for a binary tree node. * struct TreeNode { * int val; *…

题目如下: On an NxN chessboard, a knight starts at the r-th row and c-th column and attempts to make exactly K moves. The rows and columns are 0 indexed, so the top-left square is (0, 0), and the bottom-right square is (N-1, N-1). A chess knight has 8 po…

[LeetCode]Pascal's Triangle II 解题报告 标签(空格分隔): LeetCode 题目地址:https://leetcode.com/problems/pascals-triangle-ii/description/ 题目描述: Given an index k, return the kth row of the Pascal's triangle. For example, given k = 3, Return [1,3,3,1]. Note: Could yo…

[LeetCode]120. Triangle 解题报告(Python) 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址https://leetcode.com/problems/triangle/description/ 题目描述: Given a triangle, find the minimum path sum from top to bottom. Each step you may move to adjac…

[LeetCode]779. K-th Symbol in Grammar 解题报告(Python) 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址:https://leetcode.com/problems/k-th-symbol-in-grammar/description/ 题目描述: On the first row, we write a 0. Now in every subsequent row, we lo…

[LeetCode]36. Valid Sudoku 解题报告(Python) 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址:https://leetcode.com/problems/valid-sudoku/description/ 题目描述: Determine if a 9x9 Sudoku board is valid. Only the filled cells need to be validated ac…

[LeetCode]813. Largest Sum of Averages 解题报告(Python) 标签(空格分隔): LeetCode 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址:https://leetcode.com/problems/largest-sum-of-averages/description/ 题目描述: We partition a row of numbers A into at most…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 目录 题目描述 题目大意 解题方法 日期 题目地址:https://leetcode.com/problems/maximize-distance-to-closest-person/description/ 题目描述 In a row of seats, 1 represents a person sitting in that seat, and 0 represents that…

[LeetCode]554. Brick Wall 解题报告(Python) 标签(空格分隔): LeetCode 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.me/ 题目地址:https://leetcode.com/problems/brick-wall/description/ 题目描述: There is a brick wall in front of you. The wall is rectangular and has…

[LeetCode]Minimum Depth of Binary Tree Given a binary tree, find its minimum depth. The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node. 递归和非递归,此提比较简单.广度优先遍历即可.关键之处就在于如何保持访问深度. 下面是4种代码: im…