Complete Beginner Roadmap
Master the core programming skills needed for success in college coursework and personal projects
Programming Fundamentals for College & Side Projects
Focus on for-loops, arrays, and conditional logic - the building blocks of all programming.
Practice Environment
Use LeetCode Playground or your local IDE to write functions that accept parameters and test your solutions.
Get Help When Stuck
Use an LLM (like ChatGPT/Claude) to help with input parsing if needed, but focus on the core logic.
Core Skills Focus
For-loops, arrays, conditionals - the most important skills for college and side projects.
What Matters Most
Input parsing is less important - focus on problem-solving logic and algorithm thinking.
50
Fundamental Problems
Complete
Beginner Level
Filter by Difficulty
Key Concepts
Unsupported Type
You have a list of numbers and a single number. You need to check if the single number is in the list. If it is, you say 'Yes', and if it isn't, you say 'No'.
Key Concepts:
Streamer Takahashi
Takahashi is streaming from one hour to another. You need to find out how many of his listeners can watch the whole stream without missing any part of it.
Key Concepts:
Content Too Large
Takahashi has a bag and several items. He wants to know if he can fit all the items in the bag without exceeding its size limit. If the total size of the items is less than or equal to the bag's size, he can fit them all; otherwise, he cannot.
Key Concepts:
Task Failed Successfully
You need to count how many days Takahashi did more tasks than he planned. For each day, compare the number of tasks he actually completed with his goal and keep track of the days he succeeded.
Key Concepts:
Required Length
You need to check if a password made of lowercase letters is long enough. The password must be at least a certain number of characters long. If it is long enough, you say 'Yes'; if not, you say 'No'.
Key Concepts:
入力例 1
You have a number of horse races, and each race allows horses of a certain age or younger to compete. You need to find out how many races a horse of a specific age can enter.
Key Concepts:
Conflict
You have a list of items and two friends, Takahashi and Aoki, who each want some of those items. The task is to check if there is at least one item that both friends want.
Key Concepts:
Timeout
You need to check if the elder of Takahashi Village stays awake after being tapped on the shoulder a certain number of times. If the time between taps exceeds a specific limit, he will fall asleep. Your task is to find out if he stays awake until the last tap.
Key Concepts:
Approximation
You are given two numbers: a positive number A and a positive odd number B. Your task is to find the whole number that is closest to the value of A divided by B.
Key Concepts:
Not Acceptable
You need to check if a student submitted their report before a deadline. If the submission time is earlier than the deadline, you should say 'Yes'; otherwise, say 'No'.
Key Concepts:
Is it rated?
You need to check if a person's rating allows them to participate in a specific division of a contest. If their rating falls within the allowed range for that division, you will answer 'Yes'; otherwise, you will answer 'No'.
Key Concepts:
Not Found
You are given a string of lowercase letters. Your task is to find and print one letter that is not in the string.
Key Concepts:
Odd Position Sum
You have a list of numbers, and you need to add up the numbers that are in the odd positions, like the 1st, 3rd, 5th, etc. The task is to find the total of these numbers.
Key Concepts:
CBC
You need to take a string that contains both uppercase and lowercase letters and create a new string with only the uppercase letters in the same order. For example, from 'HelloWorld', you would get 'HW'.
Key Concepts:
Status Code
You will receive a number between 100 and 999. If this number is between 200 and 299, you should print 'Success'. If it is not, you should print 'Failure'.
Key Concepts:
ABC400 Party
You need to arrange 400 people in a rectangle with a given number of rows (A). Your task is to find out how many columns (B) you can have if each row must be full. If it's not possible to arrange them this way, you should return -1.
Key Concepts:
Hamming Distance
You have two strings of the same length made up of lowercase letters. Your task is to count how many positions in these strings have different letters.
Key Concepts:
Doors in the Center
You need to create a string that is a palindrome (it reads the same forwards and backwards) and is made up of the characters '-' and '='. The string must have either one '=' or two adjacent '=' characters, and it has to be a specific length that you will provide.
Key Concepts:
Thermometer
You need to check a person's body temperature and tell which category it falls into: high fever, fever, or normal. Based on the temperature, you will return a number: 1 for high fever, 2 for fever, and 3 for normal.
Key Concepts:
Triple Four
You have a list of numbers, and you need to check if any number appears three times in a row. If you find such a group of numbers, you should say 'Yes', otherwise say 'No'.
Key Concepts:
Strictly Increasing?
You need to check if a list of numbers is strictly increasing, which means each number is smaller than the next one. If all numbers follow this rule, print 'Yes'; otherwise, print 'No'.
Key Concepts:
22222
You have a string made of numbers. Your task is to keep only the number '2' from the string and remove everything else, then show the new string with only '2's in the same order they appeared.
Key Concepts:
Poisonous Oyster
You have four types of oysters, and one of them makes people sick. Two friends tried different oysters, and you need to figure out which type makes someone sick based on whether they felt fine or sick after eating.
Key Concepts:
Shuffled Equation
You have three numbers, and you can rearrange them in any order. Your task is to check if you can multiply two of the numbers together to equal the third number.
Key Concepts:
Lucky Direction
You will receive a direction as a letter (like 'N' for North or 'E' for East). Your task is to find and print the opposite direction (for example, if you get 'N', you should print 'S' for South).
Key Concepts:
12435
You have a list of five numbers that are mixed up. You need to check if you can sort them in order by swapping just two numbers that are next to each other. If you can do it, say 'Yes'; if not, say 'No'.
Key Concepts:
9x9
You are given a string with three characters. The first and third characters are numbers between 1 and 9, and the middle character is 'x'. Your task is to multiply the two numbers together and print the result.
Key Concepts:
?UPC
You need to take a word that starts with a capital letter and ends with lowercase letters. Then, combine the first letter of that word with the letters 'UPC' and print the result.
Key Concepts:
Happy New Year 2025
You need to take two positive numbers, add them together, and then find the result of that sum multiplied by itself. For example, if you add 2 and 3, you should calculate (2 + 3) * (2 + 3).
Key Concepts:
Full House 2
You have four cards with numbers on them. Your task is to check if you can add one more card to make a special combination called a Full House, which consists of three cards with one number and two cards with another number.
Key Concepts:
Equally
You are given three numbers. Your task is to find out if you can split these numbers into two or more groups where the sum of each group is the same.
Key Concepts:
aaaadaa
You have a word made of small letters. You need to change every letter that is not a specific letter to another specific letter. For example, if you want to keep 'b' and change everything else to 'g', you will replace all letters except 'b' with 'g'.
Key Concepts:
Humidifier 1
You have a humidifier that starts empty, and you will add water to it several times at different times. Each time you add water, some water will evaporate over time, and you need to find out how much water is left in the humidifier after the last addition.
Key Concepts:
Daily Cookie
You have a row of boxes, some with cookies and some empty. After a certain number of days, you will eat one cookie from a box each day. We want to find out how many boxes will be empty after those days are over.
Key Concepts:
11/22 String
You need to check if a string made of '1', '2', and '/' is an 11/22 string. An 11/22 string has an odd length, starts with '1's, has a '/' in the middle, and ends with '2's. If it follows these rules, print 'Yes'; otherwise, print 'No'.
Key Concepts:
123233
You are given a 6-digit number. Check if it has exactly one '1', two '2's, and three '3's in it. If it does, say 'Yes', otherwise say 'No'.
Key Concepts:
Cyclic
You are given a three-digit number made of digits from 1 to 9. You need to rearrange the digits in two different ways and print the new numbers you create from those arrangements.
Key Concepts:
Pairing
You have four balls, each with a color represented by a number. Your goal is to find out how many pairs of balls you can remove if you can only remove two balls of the same color at a time.
Key Concepts:
Rearranging ABC
You are given a 3-letter string made of uppercase letters. Your task is to check if you can rearrange these letters to form the word 'ABC'.
Key Concepts:
Candy Button
You have a button that gives you a candy when you press it. However, you can only get a candy if a certain amount of time has passed since you last got one. You will press the button multiple times, and you need to count how many candies you receive.
Key Concepts:
Seats
You have a row of seats that can either be occupied or empty. Your task is to count how many times there is a person sitting in seat i and seat i + 2, with an empty seat in between (seat i + 1).
Key Concepts:
Takahashi san 2
You need to check if a given word ends with 'san'. If it does, you will print 'Yes'. If it doesn't, you will print 'No'.
Key Concepts:
September
You have 12 words, and each word is numbered from 1 to 12. Your task is to count how many words have a length that matches their number (for example, the first word should have 1 letter, the second word should have 2 letters, and so on).
Key Concepts:
delete .
You are given a string that includes lowercase letters and the dot character (.). Your task is to create a new string by removing all the dots from the original string.
Key Concepts:
Jiro
You have three brothers named A, B, and C. You know who is older or younger based on three symbols (< or >). Your task is to find out which brother is the second oldest.
Key Concepts:
Raise Both Hands
You need to check which hand Snuke is raising to decide if he wants to eat takoyaki. If he raises only his left hand, he wants to eat it, and we print 'Yes'. If he raises only his right hand, we print 'No'. If he raises both hands or none, we print 'Invalid'.
Key Concepts:
369
You have two numbers, A and B. You need to find out how many different numbers, x, can be arranged with A and B to form a sequence where the difference between the first and second number is the same as the difference between the second and third number.
Key Concepts:
Cut
You have a stack of cards with numbers on them. You need to take a certain number of cards from the bottom and place them on top of the stack, then show the new order of the cards from top to bottom.
Key Concepts:
Shout Everyday
Takahashi has to shout his love for takoyaki at a specific time each day. He goes to sleep and wakes up at certain times, and we need to check if he is awake at the time he needs to shout.
Key Concepts:
Election 2
In a city election, there are two candidates: Takahashi and Aoki. You need to check if it's already clear who will win based on the votes counted so far and the total votes that can still be counted.
Key Concepts:
Your Learning Progress
0
Easy Completed
0
Medium Completed
0
Hard Completed
0
Day Streak