Easy

Problem	Pattern	Lists	Description
Add Binary	Math, String, Bit Manipulation, Simulation	Grind 75, Grind 169	Given two binary strings a and b, return their sum as a binary string
Balanced Binary Tree	Tree, Depth-First Search, Binary Tree	Grind 75, Grind 169, NeetCode 150	Given a binary tree, determine if it is height-balanced
Best Time to Buy and Sell Stock	Array, Dynamic Programming	Blind 75, Grind 75, Grind 169, NeetCode 150, Google Top 50	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
Binary Search	Array, Binary Search	Grind 75, Grind 169, NeetCode 150	Given an array of integers nums which is sorted in ascending order, and an integer target, write a function to search
Binary Tree Inorder Traversal	Stack, Tree, Depth-First Search, Binary Tree		Given the root of a binary tree, return the inorder traversal of its nodes’ values
Climbing Stairs	Math, Dynamic Programming, Memoization	Blind 75, Grind 75, Grind 169, NeetCode 150	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
Contains Duplicate	Array, Hash Table, Sorting	Blind 75, Grind 75, Grind 169, NeetCode 150	Given an integer array nums, return true if any value appears at least twice in the array, and return false if every
Contains Duplicate Ii	Array, Hash Table, Sliding Window		Given an integer array nums and an integer k, return true if there are two distinct indices i and j in the array such
Convert Sorted Array to Binary Search Tree	Array, Divide and Conquer, Tree, Binary Search Tree, Binary Tree	Grind 169	Given an integer array nums where the elements are sorted in ascending order, convert it to a height-balanced binary
Diameter of Binary Tree	Tree, Depth-First Search, Binary Tree	Grind 75, Grind 169, NeetCode 150	Given the root of a binary tree, return the length of the diameter of the tree. The diameter of a binary tree is the
Find the Index of the First Occurrence in a String	Two Pointers, String, String Matching		Given two strings needle and haystack, return the index of the first occurrence of needle in haystack, or -1 if needle
First Unique Character in a String	Hash Table, String, Queue, Counting		Given a string s, find the first non-repeating character in it and return its index. If it does not exist, return -1
Fizz Buzz	Math, String, Simulation		Given an integer n, return a string array answer ( 1-indexed ) where: - answer[i] == “FizzBuzz” if i is divisible by
Happy Number	Hash Table, Math, Two Pointers	NeetCode 150, Google Top 50	Write an algorithm to determine if a number n is happy. A happy number is a number defined by the following process: -
Intersection Of Two Arrays Ii	Array, Hash Table, Two Pointers, Binary Search, Sorting		Given two integer arrays nums1 and nums2, return an array of their intersection. Each element in the result must
Intersection Of Two Linked Lists	Hash Table, Linked List, Two Pointers		Given the heads of two singly linked-lists headA and headB, return the node at which the two lists intersect. If the
Invert Binary Tree	Tree, Depth-First Search, Breadth-First Search, Binary Tree	Blind 75, Grind 75, Grind 169, NeetCode 150	Given the root of a binary tree, invert the tree, and return its root
Is Subsequence	Two Pointers, String, Dynamic Programming		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
Isomorphic Strings	Hash Table, String		Given two strings s and t, determine if they are isomorphic. Two strings s and t are isomorphic if the characters in s
Kth Largest Element in a Stream	Tree, Design, Binary Search Tree, Heap (Priority Queue), Binary Tree, Data Stream	NeetCode 150	You are part of a university admissions office and need to keep track of the kth highest test score from applicants in
Last Stone Weight	Array, Heap (Priority Queue)	NeetCode 150	You are given an array of integers stones where stones[i] is the weight of the i :sup:th stone. We are playing a
Length Of Last Word	String		Given a string s consisting of words and spaces, return the length of the last word in the string. A word is a
Linked List Cycle	Hash Table, Linked List, Two Pointers	Blind 75, Grind 75, Grind 169, NeetCode 150	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
Longest Common Prefix	Array, String, Trie	Grind 169, Google Top 50	Write a function to find the longest common prefix string amongst an array of strings. If there is no common prefix,
Majority Element	Array, Hash Table, Divide and Conquer, Sorting, Counting	Grind 75, Grind 169	Given an array nums of size n, return the majority element. The majority element is the element that appears more than
Maximum Depth of Binary Tree	Tree, Depth-First Search, Breadth-First Search, Binary Tree	Blind 75, Grind 75, Grind 169, NeetCode 150	Given the root of a binary tree, return its maximum depth. A binary tree’s maximum depth is the number of nodes along
Merge Sorted Array	Array, Two Pointers, Sorting		You are given two integer arrays nums1 and nums2, sorted in non-decreasing order, and two integers m and n,
Merge Two Sorted Lists	Linked List, Recursion	Blind 75, Grind 75, Grind 169, NeetCode 150	You are given the heads of two sorted linked lists list1 and list2. Merge the two lists into one sorted list. The list
Min Cost Climbing Stairs	Array, Dynamic Programming	NeetCode 150	You are given an integer array cost where cost[i] is the cost of i :sup:th step on a staircase. Once you pay the
Missing Number	Array, Hash Table, Math, Binary Search, Bit Manipulation, Sorting	Blind 75, Grind 169, NeetCode 150	Given an array nums containing n distinct numbers in the range [0, n], return the only number in the range that is
Palindrome Linked List	Linked List, Two Pointers, Stack, Recursion	Grind 169	Given the head of a singly linked list, return true if it is a palindrome or false otherwise
Palindrome Number	Math	Grind 169, Google Top 50	Given an integer x, return true if x is a palindrome , and false otherwise
Pascals Triangle	Array, Dynamic Programming		Given an integer numRows, return the first numRows of Pascal’s triangle. In Pascal’s triangle, each number is the
Plus One	Array, Math	NeetCode 150	You are given a large integer represented as an integer array digits, where each digits[i] is the i :sup:th digit of
Power Of Three	Math, Recursion		Given an integer n, return true if it is a power of three. Otherwise, return false. An integer n is a power of three,
Ransom Note	Hash Table, String, Counting	Grind 75, Grind 169	Given two strings ransomNote and magazine, return true if ransomNote can be constructed by using the letters from
Remove Element	Array, Two Pointers		Given an integer array nums and an integer val, remove all occurrences of val in nums in-place
Reverse Linked List	Linked List, Recursion	Blind 75, Grind 75, Grind 169, NeetCode 150	Given the head of a singly linked list, reverse the list, and return the reversed list
Reverse String	Two Pointers, String		Write a function that reverses a string. The input string is given as an array of characters s. You must do this by
Roman to Integer	Hash Table, Math, String	Grind 169, Google Top 50	Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M. :: Symbol Value I
Same Tree	Tree, Depth-First Search, Breadth-First Search, Binary Tree	Blind 75, Grind 169, NeetCode 150	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
Sqrtx	Math, Binary Search		Given a non-negative integer x, return the square root of x rounded down to the nearest integer. The returned integer
Subtree of Another Tree	Tree, Depth-First Search, String Matching, Binary Tree, Hash Function	Blind 75, Grind 169, NeetCode 150	Given the roots of two binary trees root and subRoot, return true if there is a subtree of root with the same structure
Summary Ranges	Array		You are given a sorted unique integer array nums. A range [a,b] is the set of all integers from a to b (inclusive)
Symmetric Tree	Tree, Depth-First Search, Breadth-First Search, Binary Tree	Grind 169	Given the root of a binary tree, check whether it is a mirror of itself (i.e., symmetric around its center)
Two Sum	Array, Hash Table	Blind 75, Grind 75, Grind 169, NeetCode 150, Google Top 50	Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to
Valid Anagram	Hash Table, String, Sorting	Blind 75, Grind 75, Grind 169, NeetCode 150	Given two strings s and t, return true if t is an anagram of s, and false otherwise
Valid Palindrome	Two Pointers, String	Blind 75, Grind 75, Grind 169, NeetCode 150	A phrase is a palindrome if, after converting all uppercase letters into lowercase letters and removing all
Valid Parentheses	String, Stack	Blind 75, Grind 75, Grind 169, NeetCode 150	Given a string s containing just the characters ‘(’, ‘)’, ‘{’, ‘}’, ‘[’ and ‘]’, determine if the input string is
Word Pattern	Hash Table, String		Given a pattern and a string s, find if s follows the same pattern. Here follow means a full match, such that there is