Rafael Leme Costa’s Post

🔥 Day 17 of My LeetCode Journey — Problem #377: Combination Sum IV (Dynamic Programming) Today’s focus was on Dynamic Programming — specifically tackling problems where order matters in combinations. 🧩 Problem Summary: Given an array of distinct integers and a target integer, the task was to compute the number of possible combinations that sum up to the target. 💡 Approach & Key Insights: Utilized bottom-up Dynamic Programming (1D array approach) to efficiently compute results. Base case: dp[0] = 1, representing one way to reach a sum of zero. Iteratively built combinations where the sequence order impacts the outcome, differentiating it from subset problems. ⚙️ Algorithmic Complexity: Time: O(n × target) Space: O(target) 📈 Performance Outcome: ✅ Accepted Solution ⚡ Runtime: 1 ms (Beats 67.14% of Java submissions) 💾 Memory: 41.19 MB Each day’s challenge continues to refine my analytical reasoning and problem-solving efficiency, bringing me one step closer to mastering algorithmic design patterns in Java. #LeetCode #Java #DynamicProgramming #CodingJourney #ProblemSolving #TechLearning #SoftwareEngineering

🚀 Day-74 of #100DaysOfCodeChallenge 💡 LeetCode Problem: 3370. Smallest Number With All Set Bits (Easy) 🧠 Concepts Practiced: Bit Manipulation, Binary Representation, Logical Thinking Today’s challenge was short but conceptually sharp — finding the smallest number ≥ n whose binary representation consists only of 1’s (all set bits). This problem tested understanding of bit patterns and how to efficiently generate numbers with consecutive set bits using bitwise logic. 🔹 Key Idea: Keep generating numbers of the form (1 << k) - 1 (which gives 111...1 in binary) until we find one greater than or equal to n. It’s a neat example of how mathematical patterns meet binary logic in programming! ⚙️ ⚙️ Language: Java ⚡ Runtime: 0 ms (Beats 100.00%) 💾 Memory: 40.59 MB (Beats 87.17%) ✅ Result: 608 / 608 test cases passed — Accepted 🎯 Every problem, no matter how simple, reinforces that clarity in logic is the foundation of clean code 💪 #100DaysOfCode #LeetCode #Java #CodingChallenge #BitManipulation #BinaryLogic #ProblemSolving #Programming #DeveloperJourney #LearningEveryday #TechMindset #CleanCode

Reflecting on a fundamental concept today: the journey from struct in C to class in Java! 💡 I was thinking about how C's struct allowed us to group related data, providing a powerful way to organize information. But then, the jump to class in Java introduced a revolutionary idea: not just grouping data, but also encapsulating the functions (methods) that operate on that data. This isn't just about syntax; it's a paradigm shift. Classes enable us to model real-world entities much more closely, where data and its behavior are inherently linked. It brings us closer to the principles of Object-Oriented Programming, promoting better organization, reusability, and maintainability in our code. It's a beautiful evolution in how we think about and structure our programs. What are your thoughts on this progression? #Programming #C #Java #OOP #SoftwareDevelopment #Structs #Classes #Tech Here's an image that visualizes this concept generated by Gemini :

🧠 Day 13: Understanding Loops and Operators in Java Today, I took a deep dive into loops and operators — the real backbone of logical thinking in programming. When I first saw loops, they felt tricky. But once I started solving problems, I realized they’re just smart ways to repeat tasks — and operators help us make decisions inside them. 💻 Here’s what I practiced today: Sum or Product of numbers Terms of an Arithmetic Progression (AP) Reverse of a number Binary ↔ Decimal conversions Square root calculation Checking number sequence Pattern problems: ➤ Mirror number pattern ➤ Inverted number pattern ➤ Star pattern ➤ Triangle of numbers ➤ Diamond of stars ✨ Each problem taught me how to control logic flow, use nested loops effectively, and think step by step like a programmer. 🚀 Every loop I wrote made me more confident about how code really works behind the scenes. 💬 What was the first programming concept that made things finally “click” for you? #Java #Loops #Operators #CodingJourney #ProblemSolving #100DaysOfCode #LearningDSA #CodeNewbie #TechLearning #NeverStopLearning #WomenInTech #BuildInPublic #DeveloperJourney #CodingCommunity #LearnJava #ProgrammingBasics #KeepCoding #CodeNewbie #TechJourney

🚀 Day-73 of #100DaysOfCodeChallenge 💡 LeetCode Problem: 3354. Make Array Elements Equal to Zero (Easy) 🧠 Concepts Practiced: Simulation, Array Manipulation, Direction Reversal Logic Today’s problem was all about simulating a dynamic process — starting from a zero element in an array, moving in a chosen direction, and adjusting movement logic as the array updates. It’s a great exercise in understanding flow control and direction-based simulation, where small logical errors can change the entire outcome. Patience and precision made all the difference here. 🔹 Approach: Simulated each possible starting point and direction, tracking movements and reversals until all elements became zero. Focus was on correctness and clear logic rather than over-optimization. ⚙️ Language: Java ⚡ Runtime: 100 ms (Beats 23.49%) 💾 Memory: 43.44 MB (Beats 13.25%) ✅ Result: 584 / 584 test cases passed — Accepted 🎯 Each solved problem reminds me how logic, structure, and consistency build stronger foundations for solving complex challenges ahead 💪 #100DaysOfCode #LeetCode #Java #CodingChallenge #ProblemSolving #Programming #DeveloperJourney #TechMindset #LearningEveryday #Consistency #Simulation

🚀 Day 140 of #150DaysOfCode on LeetCode Solved: 1526. Minimum Number of Increments on Subarrays to Form a Target Array Language: Java The task was to determine the minimum number of subarray increment operations needed to build the target array from all zeros. 🔹 Intuition: Every time the current element is greater than the previous one, it means we need that many new operations to reach the next level. Decreases don’t add extra work since earlier increments already cover them. 🔹 Approach: Start with the first element’s value as the initial count. For each subsequent element, if it’s larger than the previous one, add the difference. The sum of all such differences gives the minimum number of operations required. 🔹 Complexity: Time: O(n) Space: O(1) #LeetCode #150DaysOfCode #Java #CodingChallenge #ProblemSolving #Greedy #Arrays #DSA #TechLearning #Programmer #WomenInTech #CodeJourney #DynamicProgramming

🚀 Day 129/160 – Total Decoding Messages | Dynamic Programming Today’s challenge was about decoding numeric messages into alphabets (like 1→A, 2→B...26→Z). Used a DP approach to count all valid decoding ways efficiently. 🧠 Key takeaway: Dynamic Programming shines when a problem’s state depends on previous results — here, each position depends on the previous one and the one before it. #100DaysOfCode #GeeksforGeeks #160DaysOfDSA #DynamicProgramming #ProblemSolving #Java #CodingJourney #LearnByDoing

Recently, I got curi🤔us about how high-level languages like Go, Java, or Rust are actually built. Do they all start from assembly? Turns out, not all high-level languages start from assembly. Take Go (Golang) as an example, the first Go compiler that turned Go code into machine code was written in C, not assembly. As Go matured, this C-based compiler was replaced by a new compiler written in Go itself. This fascinating process is called bootstrapping, it’s when a programming language’s compiler is written in the same language it compiles. In other words, the language learns to build itself. #golang #rustlang #bootstrapping #compiler #java #SoftwareDevelopment #Programming #GoDeveloper #SoftwareEngineering

"Exploring the Magic of Loops in Java! 💻✨ From simple triangles to complex symmetric designs, star patterns are more than just beginner exercises — they’re a creative way to master logic, loops, and nested conditions! Here’s my deep dive into different star pattern programs in Java — each one crafted to teach how iterations and conditions interact to create stunning console outputs. Programming isn’t just about solving problems; it’s about creating beauty through logic. 🌟 #JavaProgramming #CodingJourney #PatternLogic #ProgrammersLife #CodeArt #TechLearning #StarPattern #LogicBuilding"

🔹 Day 40 – LeetCode Practice Problem: Find Greatest Common Divisor of Array (LeetCode #1979) 📌 Problem Statement: Given an integer array nums, find the greatest common divisor (GCD) of the smallest and largest numbers in the array. ✅ My Approach (Java): 1. Find the minimum and maximum elements in the array. 2. Starting from the smaller number and going downwards, check for the highest integer that divides both min and max. 3. Return that integer as the GCD. 📊 Complexity: Time Complexity: O(n + min(a, b)) Space Complexity: O(1) ⚡ Submission Results: Accepted ✅ Runtime: 0 ms (Beats 100%) 🚀 Memory: 43.41 MB (Beats 41.55%) 💡 Reflection: This problem shows how basic math logic and loop optimization can lead to extremely efficient solutions. A simple and powerful way to practice number theory in coding! #LeetCode #ProblemSolving #Java #DSA #CodingPractice #Learning