Graphs & Trees Deep Dive

Return every root-to-leaf path in a binary tree as a list of node values, instead of an arrow-joined string.

An introduction to the Node and BinTree building blocks used throughout the Binary Trees series, plus a sample tree these exercises build on.

Return every root-to-leaf path in a binary tree as an arrow-joined string.

Add preorder, inorder, and postorder traversal methods to BinTree and see how each visits the same sample tree in a different order.

Build a height-balanced binary search tree from an array sorted in ascending order.

Flip a binary tree into its mirror image by swapping every node's left and right children.

Find the smallest absolute difference between the values of any two distinct nodes in a binary search tree.

Sum every node value in a binary search tree that falls within a given inclusive range.

Find the node with a given value in a binary search tree and return the subtree rooted there.

Determine whether a binary tree is a mirror of itself around its center.

Return the value of the leftmost node visible at each level of a binary tree, from top to bottom.

Print the first node visible at each level of the sample tree, extending level order traversal with a single boolean flag.

Add a queue-based level order (breadth-first) traversal to BinTree, visiting the sample tree one level at a time.

There is a binary tree rooted at 0 consisting of n nodes.

Remove the node with a given value from a binary search tree while preserving its ordering property.

Insert a new value into a binary search tree while preserving its ordering property.

Find the k-th smallest value stored in a binary search tree.

Find the lowest common ancestor of two given values in a binary search tree, using the tree's ordering to avoid a generic tree search.

Given an integer n, return the number of structurally unique BST's (binary search trees) which has exactly n nodes of unique values from 1 to n.

Determine whether a binary tree satisfies the binary search tree property at every node, not just between direct parent-child pairs.

Given an array nums that represents a permutation of integers from 1 to n.

There is a bi-directional graph with n vertices, where each vertex is labeled from 0 to n - 1 (inclusive).

You are given an image represented by an m x n grid of integers image, where image[i][j] represents the pixel value of the image.

You are given row x col grid representing a map where grid[i][j] = 1 represents land and grid[i][j] = 0 represents water.

Given an m x n binary matrix mat, return the distance of the nearest 0 for each cell.

Given a list of accounts where each element accounts[i] is a list of strings, where the first element accounts[i][0] is a name, and the rest of the elements are emails...

Given a directed acyclic graph (DAG) of n nodes labeled from 0 to n - 1, find all possible paths from node 0 to node n - 1 and return them in any order.

You are given an integer array nums of length n where nums is a permutation of the numbers in the range [0, n - 1].

Given an n x n grid containing only values 0 and 1, where 0 represents water and 1 represents land, find a water cell such that its distance to the nearest land cell is maximized,...

Given an m x n matrix board where each cell is a battleship 'X' or empty '.', return the number of the battleships on board.

There is a room with n bulbs labeled from 1 to n that all are turned on initially, and four buttons on the wall.

There are n cities connected by some number of flights.

You are given an m x n grid.

There is a knight on an n x n chessboard.

You are given an integer array coins representing coins of different denominations and an integer amount representing a total amount of money.

You are given an m x n matrix grid and a positive integer k.

You are given a map of a server center, represented as a m * n integer matrix grid, where 1 means that on that cell there is a server and 0 means that it is no server.

You are given two m x n binary matrices grid1 and grid2 containing only 0's (representing water) and 1's (representing land).

You are given an integer n.

You are given an integer n.

Given a 2D array of characters grid of size m x n, you need to find if there exists any cycle consisting of the same value in grid.

You are given an array of variable pairs equations and an array of real numbers values, where equations[i] = [Ai, Bi] and values[i] represent the equation Ai / Bi = values[i].

You are given a 0-indexed 2D matrix grid of size n x n, where (r, c) represents: You are initially positioned at cell (0, 0).

There is an undirected graph with n nodes, where each node is numbered between 0 and n - 1.

You are given two strings of the same length s1 and s2 and a string baseStr.

Given an unsorted array of integers nums, return the length of the longest consecutive elements sequence.

You are given a 0-indexed array of positive integers nums and a positive integer limit.

You are given an m x n binary matrix grid.

You are given a 0-indexed 2D matrix grid of size m x n, where (r, c) represents: A fisher can start at any water cell (r, c) and can do the following operations any number of...

There are a total of numCourses courses you have to take, labeled from 0 to numCourses - 1.

There are a total of numCourses courses you have to take, labeled from 0 to numCourses - 1.

There are a total of numCourses courses you have to take, labeled from 0 to numCourses - 1.

You are given two integers n and m that consist of the same number of digits.

You are given an m x n binary matrix grid and an integer health.

You have information about n different recipes.

There is a directed graph of n nodes with each node labeled from 0 to n - 1.

There is a dungeon with n x m rooms arranged as a grid.

There is a dungeon with n x m rooms arranged as a grid.

There are n cities numbered from 0 to n-1.

There is a group of n people labeled from 0 to n - 1 where each person has a different amount of money and a different level of quietness.

You are given two integers, n and threshold, as well as a directed weighted graph of n nodes numbered from 0 to n - 1.

You are given an array start where start = [startX, startY] represents your initial position (startX, startY) in a 2D space.

You are given two 0-indexed strings source and target, both of length n and consisting of lowercase English letters.