Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M.

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 depth d. The root node is at depth 1.

Given a string s consisting only of letters ‘a’ and ‘b’. In a single step you can remove one palindromic subsequence from s.

Design a HashMap without using any built-in hash table libraries.

A valid encoding of an array of words is any reference string s and array of indices indices such that:

Write a program to find the node at which the intersection of two singly linked lists begins.

Given an array nums and a value val, remove all instances of that value in-place and return the new length.

Given an array nums containing n distinct numbers in the range [0, n], return the only number in the range that is missing from the array.

You have a set of integers s, which originally contains all the numbers from 1 to n. Unfortunately, due to some error, one of the numbers in s got duplicated to another number in the set, which results in repetition of one number and loss of another number.

Alice has n candies, where the ith candy is of type candyType[i]. Alice noticed that she started to gain weight, so she visited a doctor.