Easy ==== - :doc:`Add Binary ` -- Given two binary strings a and b, return *their sum as a binary string*. - :doc:`Best Time To Buy And Sell Stock ` -- You are given an array prices where prices[i] is the price of a given stock on the i\ :sup:`th` day. You want to... - :doc:`Binary Tree Inorder Traversal ` -- Given the root of a binary tree, return *the inorder traversal of its nodes' values*. - :doc:`Climbing Stairs ` -- You are climbing a staircase. It takes n steps to reach the top. Each time you can either climb 1 or 2 steps. In how... - :doc:`Contains Duplicate II ` -- Given an integer array nums and an integer k, return true if there are two distinct indices i and j *in the array such... - :doc:`Convert Sorted Array To BST ` -- Given an integer array nums where the elements are sorted in ascending order, convert it to a height-balanced *binary... - :doc:`Find The Index Of The First Occurrence In A String ` -- Given two strings needle and haystack, return the index of the first occurrence of needle in haystack, or -1 if needle... - :doc:`First Unique Character In A String ` -- Given a string s, find the first non-repeating character in it and return its index. If it does not exist, return -1. - :doc:`Fizz Buzz ` -- Given an integer n, return a string array answer (\ 1-indexed\ ) where: - answer[i] == "FizzBuzz" if i is divisible by... - :doc:`Happy Number ` -- Write an algorithm to determine if a number n is happy. A happy number is a number defined by the following process: -... - :doc:`Intersection Of Two Arrays II ` -- Given two integer arrays nums1 and nums2, return *an array of their intersection*. Each element in the result must... - :doc:`Intersection Of Two Linked Lists ` -- Given the heads of two singly linked-lists headA and headB, return the node at which the two lists intersect. If the... - :doc:`Invert Binary Tree ` -- Given the root of a binary tree, invert the tree, and return *its root*. - :doc:`Is Subsequence ` -- Given two strings s and t, return true if s is a subsequence of t\ , or false otherwise. A subsequence of a string is a... - :doc:`Isomorphic Strings ` -- Given two strings s and t, determine if they are isomorphic. Two strings s and t are isomorphic if the characters in s... - :doc:`Length Of Last Word ` -- Given a string s consisting of words and spaces, return *the length of the last word in the string.* A word is a... - :doc:`Linked List Cycle ` -- Given head, the head of a linked list, determine if the linked list has a cycle in it. There is a cycle in a linked... - :doc:`Longest Common Prefix ` -- Write a function to find the longest common prefix string amongst an array of strings. If there is no common prefix,... - :doc:`Majority Element ` -- Given an array nums of size n, return the majority element. The majority element is the element that appears more than... - :doc:`Maximum Depth Of Binary Tree ` -- Given the root of a binary tree, return its maximum depth. A binary tree's maximum depth is the number of nodes along... - :doc:`Merge Sorted Array ` -- You are given two integer arrays nums1 and nums2, sorted in non-decreasing order, and two integers m and n,... - :doc:`Merge Two Sorted Lists ` -- You are given the heads of two sorted linked lists list1 and list2. Merge the two lists into one sorted list. The list... - :doc:`Missing Number ` -- Given an array nums containing n distinct numbers in the range [0, n], return *the only number in the range that is... - :doc:`Palindrome Linked List ` -- Given the head of a singly linked list, return true if it is a palindrome or false otherwise. - :doc:`Palindrome Number ` -- Given an integer x, return true if x is a palindrome\ *, and false otherwise*. - :doc:`Pascals Triangle ` -- Given an integer numRows, return the first numRows of **Pascal's triangle**. In Pascal's triangle, each number is the... - :doc:`Plus One ` -- You are given a large integer represented as an integer array digits, where each digits[i] is the i\ :sup:`th` digit of... - :doc:`Power Of Three ` -- Given an integer n, return *true if it is a power of three. Otherwise, return false*. An integer n is a power of three,... - :doc:`Ransom Note ` -- Given two strings ransomNote and magazine, return true if ransomNote can be constructed by using the letters from... - :doc:`Remove Element ` -- Given an integer array nums and an integer val, remove all occurrences of val in nums `in-place... - :doc:`Reverse Linked List ` -- Given the head of a singly linked list, reverse the list, and return the reversed list. - :doc:`Reverse String ` -- Write a function that reverses a string. The input string is given as an array of characters s. You must do this by... - :doc:`Roman To Integer ` -- Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M. :: Symbol Value I ... - :doc:`Same Tree ` -- Given the roots of two binary trees p and q, write a function to check if they are the same or not. Two binary trees... - :doc:`Sqrtx ` -- Given a non-negative integer x, return the square root of x rounded down to the nearest integer. The returned integer... - :doc:`Summary Ranges ` -- You are given a sorted unique integer array nums. A range [a,b] is the set of all integers from a to b (inclusive).... - :doc:`Symmetric Tree ` -- Given the root of a binary tree, *check whether it is a mirror of itself* (i.e., symmetric around its center). - :doc:`Two Sum ` -- Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to... - :doc:`Valid Anagram ` -- Given two strings s and t, return true if t is an anagram of s, and false otherwise. - :doc:`Valid Palindrome ` -- A phrase is a palindrome if, after converting all uppercase letters into lowercase letters and removing all... - :doc:`Valid Parentheses ` -- Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is... - :doc:`Word Pattern ` -- Given a pattern and a string s, find if s follows the same pattern. Here follow means a full match, such that there is...