We are to write the letters of a given string S, from left to right into lines. Each line has maximum width 100 units, and if writing a letter would cause the width of the line to exceed 100 units,…

A website domain like “discuss.leetcode.com” consists of various subdomains. At the top level, we have “com”, at the next level, we have “leetcode.com”, and at the lowest level, “discuss.leetcode.c…

On a 2 dimensional grid with R rows and C columns, we start at (r0, c0) facing east.

Given a non-empty, singly linked list with head node head, return a middle node of linked list.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

The transpose of a matrix is the matrix flipped over it’s main diagonal, switching the row and column indices of the matrix.

Given an array A of integers, for each integer A[i] we may choose any x with -K <= x <= K, and add x to A[i].

On a N * N grid, we place some 1 * 1 * 1 cubes that are axis-aligned with the x, y, and z axes.

Given an n-ary tree, return the postorder traversal of its nodes’ values.

Given the root node of a binary search tree (BST) and a value. You need to find the node in the BST that the node’s value equals the given value. Return the subtree rooted with that node. If such n…