LeetCode on Junian Dev

Fizz Buzz - LeetCode in C#

author@junian.dev (Junian Triajianto) — Thu, 14 Nov 2024 12:01:57 +0700

The Fizz Buzz problem is a classic exercise that is often used to teach basic programming concepts such as loops and conditionals.

In this article, I’ll show you my attempt to solve this problem.

Problem Description

Given an integer n, return a string array answer (1-indexed) where:

answer[i] == "FizzBuzz" if i is divisible by 3 and 5.
answer[i] == "Fizz" if i is divisible by 3.
answer[i] == "Buzz" if i is divisible by 5.
answer[i] == i (as a string) if none of the above conditions are true.

Example 1:

Input: n = 3
Output: ["1","2","Fizz"]

Example 2:

Input: n = 5
Output: ["1","2","Fizz","4","Buzz"]

Example 3:

Input: n = 15
Output: ["1","2","Fizz","4","Buzz","Fizz","7","8","Fizz","Buzz","11","Fizz","13","14","FizzBuzz"]

Constraints:

1 <= n <= 10⁴

Intuition

When breaking down the problem, the task is to iterate through a sequence of numbers while applying simple divisibility rules to determine the correct output for each number.

Palindrome Number - LeetCode in C#

author@junian.dev (Junian Triajianto) — Sun, 10 Nov 2024 17:03:55 +0700

Problem

Given an integer x, return true if x is a palindrome , and false otherwise.

Example 1:

Input: x = 121
Output: true
Explanation: 121 reads as 121 from left to right and from right to left.

Example 2:

Input: x = -121
Output: false
Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.

Example 3:

Input: x = 10
Output: false
Explanation: Reads 01 from right to left. Therefore it is not a palindrome.

Constraints:

Remove Duplicates From Sorted Array - LeetCode in C#

author@junian.dev (Junian Triajianto) — Sat, 09 Nov 2024 14:46:13 +0700

Problem Description

Given an integer array nums sorted in non-decreasing order, remove the duplicates in-place such that each unique element appears only once. The relative order of the elements should be kept the same. Then return the number of unique elements in nums.

Consider the number of unique elements of nums to be k, to get accepted, you need to do the following things:

Change the array nums such that the first k elements of nums contain the unique elements in the order they were present in nums initially. The remaining elements of nums are not important as well as the size of nums.
Return k.

Custom Judge:

Two Sum - LeetCode in C# - Hash Table Solution

author@junian.dev (Junian Triajianto) — Fri, 08 Nov 2024 18:51:32 +0700

Problem

Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.

You can return the answer in any order.

Example 1:

Input: nums = [2,7,11,15], target = 9
Output: [0,1]
Explanation: Because nums[0] + nums[1] == 9, we return [0, 1].

Example 2:

Two Sum - LeetCode in C# - Brute force approach

author@junian.dev (Junian Triajianto) — Fri, 08 Nov 2024 13:39:47 +0700

You might want to read the Hash Table solution. It’s better.

Intuition

When I first encountered the Two Sum problem, my initial thought was to check each possible pair of numbers in the array. If a pair sums to the target value, then that would be our solution.

This brute force method should work, but intuitively, I thought there might be more efficient ways.

However, starting with the simplest idea often helps to understand the problem better and refine the approach.