Min Swaps for Binary Grid LeetCode Challenge

🚀 Day 29 of 100 Days LeetCode Challenge Problem: Check if Strings Can be Made Equal With Operations I Day 29 is a short but pattern + constraint observation problem 🔥 💡 Key Insight: We can only swap characters where: 👉 j - i = 2 For a string of length 4, possible swaps: Index 0 ↔ 2 Index 1 ↔ 3 👉 That means: Positions (0,2) form one group Positions (1,3) form another group 🔍 Core Approach: 1️⃣ Group Characters Extract characters from: Even indices → [0, 2] Odd indices → [1, 3] 2️⃣ Compare Groups Sort both groups for s1 and s2 If both corresponding groups match → ✅ true Else → ❌ false 💡 Why This Works: You can rearrange freely within each group But cannot mix between groups 🔥 What I Learned Today: Limited operations define independent groups Think in terms of index grouping Small problems still test logical clarity 📈 Challenge Progress: Day 29/100 ✅ One day to 30! LeetCode, Strings, Swapping, Greedy, Pattern Recognition, Arrays, DSA Practice, Coding Challenge, Problem Solving #100DaysOfCode #LeetCode #DSA #CodingChallenge #Strings #ProblemSolving #TechJourney #ProgrammerLife #SoftwareDeveloper #CodingLife #LearnToCode #Developers #Consistency #GrowthMindset #InterviewPrep

🚀 Day 6 of 100 Days LeetCode Challenge Problem: Check if Binary String Has at Most One Segment of Ones Today’s problem is all about pattern observation in strings—simple, but easy to overthink. 💡 Key Insight: The string should contain only one continuous block of '1's. 👉 That means: Once a 0 appears after a 1, There should be no more '1's later 🔍 Simplest Trick: Just check if the pattern "01" appears more than once OR even better → check if "10" appears followed by another "1" 💡 Cleaner approach: Traverse the string Count transitions from 1 → 0 If you ever see 1 again after that → ❌ Invalid 🔥 What I Learned Today: Many problems are just pattern validation Clean logic beats complex conditions Always try to reduce the problem to a simple rule 📈 Challenge Progress: Day 6/100 ✅ Consistency building strong! LeetCode, Strings, Pattern Recognition, Greedy, DSA Practice, Coding Challenge, Problem Solving, Algorithm Thinking, Programming #100DaysOfCode #LeetCode #DSA #CodingChallenge #Strings #ProblemSolving #TechJourney #ProgrammerLife #SoftwareDeveloper #CodingLife #LearnToCode #Developers #Consistency #GrowthMindset #InterviewPrep

🚀 Day 5 of 100 Days LeetCode Challenge Problem: Minimum Changes To Make Alternating Binary String Today’s problem is a perfect example of pattern comparison + greedy thinking. 💡 Key Insight: An alternating string can only be in two possible forms: "010101..." "101010..." 🔍 Approach: Compare the given string with both patterns Count mismatches for each pattern The minimum mismatch count = minimum operations required 👉 No need for complex logic—just check both possibilities and pick the best. 🔥 What I Learned Today: Always check if a problem has limited possible patterns Comparing with ideal cases can simplify logic Greedy approach helps in minimizing operations quickly 📈 Challenge Progress: Day 5/100 ✅ Strong consistency! LeetCode, Greedy Algorithm, Strings, Pattern Matching, DSA Practice, Coding Challenge, Problem Solving, Algorithm Thinking, Optimization #100DaysOfCode #LeetCode #DSA #CodingChallenge #GreedyAlgorithm #Strings #ProblemSolving #TechJourney #ProgrammerLife #SoftwareDeveloper #CodingLife #LearnToCode #Developers #Consistency #GrowthMindset #InterviewPrep

🚀 Day 7 of 100 Days LeetCode Challenge Problem: Minimum Number of Flips to Make the Binary String Alternating Today’s problem leveled up the difficulty with a mix of sliding window + string rotation + greedy logic. 💡 Key Insight: We can rotate the string (Type-1 operation), which means we should consider all possible rotations of the string. 👉 Trick: Double the string → s + s to simulate rotations Compare every window of size n with: "010101..." "101010..." 🔍 Approach: Use sliding window on the doubled string Count mismatches for both patterns Minimum flips across all windows = final answer 🔥 What I Learned Today: Rotation problems → think of string doubling Sliding window helps optimize repeated checks Combining multiple concepts = real DSA growth 📈 Challenge Progress: Day 7/100 ✅ One full week completed! LeetCode, Sliding Window, Strings, Greedy Algorithm, Pattern Matching, DSA Practice, Coding Challenge, Problem Solving, Optimization #100DaysOfCode #LeetCode #DSA #CodingChallenge #SlidingWindow #Strings #GreedyAlgorithm #ProblemSolving #TechJourney #ProgrammerLife #SoftwareDeveloper #CodingLife #LearnToCode #Developers #Consistency #GrowthMindset #InterviewPrep

100 LeetCode problems solved ! and honestly, it's taught me more about thinking than coding. When I started, I used to jump straight to the solution. Now I've learned to slow down — understand the problem, think brute force first, then optimize. Patterns I've been focusing on: → Sliding Window → Two Pointers → Stack & Queue → Kadane's Algorithm → Prefix Sum → Merge Intervals → Linked List The biggest shift wasn't in the number of problems solved — it was learning to recognize WHY a particular approach works, not just HOW. Still a long way to go. But consistency is starting to show results. 100 done. More to come. 🎯 #DSA #LeetCode #CodingJourney #SoftwareEngineering #100Problems

🚀 Day 51 of my LeetCode Journey Solved: Roman to Integer At first glance, this problem looks simple — just map symbols to numbers. But the real catch is handling subtractive cases like IV (4), IX (9), etc. 💡 Key Learning: Instead of blindly adding values, you need to compare current and next characters: If current < next → subtract Else → add This small twist is what separates a correct solution from a wrong one. 📊 Result: ✅ Accepted ⏱️ Runtime: 6 ms 📌 Takeaway: Even “easy” problems test your attention to detail. Don’t underestimate them. Consistency > Motivation. See you on Day 52. #LeetCode #DSA #CodingJourney #ProblemSolving #Consistency

🚀 Day 14 of 100 Days LeetCode Challenge Problem: The K-th Lexicographical String of All Happy Strings of Length n Today’s problem is a perfect blend of Backtracking + Lexicographical Ordering 🔥 💡 Key Insight: A happy string: Uses only 'a', 'b', 'c' No two adjacent characters are the same 👉 Instead of generating all strings blindly, we: Build valid strings using backtracking Maintain lexicographical order naturally 🔍 Core Approach: 1️⃣ Backtracking (DFS) Start building string character by character At each step: Choose from 'a', 'b', 'c' Skip if same as previous character 2️⃣ Lexicographical Order Always try characters in order: 'a' → 'b' → 'c' 3️⃣ Stop Early Once we reach the k-th string, stop recursion 👉 If total strings < k → return "" 🔥 What I Learned Today: Backtracking is powerful for constraint-based generation Ordering decisions early helps avoid extra sorting Early stopping = major optimization 📈 Challenge Progress: Day 14/100 ✅ 2 weeks strong! LeetCode, Backtracking, Recursion, Lexicographical Order, Strings, DFS, DSA Practice, Coding Challenge, Problem Solving #100DaysOfCode #LeetCode #DSA #CodingChallenge #Backtracking #Recursion #Strings #ProblemSolving #TechJourney #ProgrammerLife #SoftwareDeveloper #CodingLife #LearnToCode #Developers #Consistency #GrowthMindset #InterviewPrep

🚀 Day 41 | 100 Days of Coding Challenge #DrGViswanathanChallenge 📘 Problem Solved: Remove K Digits (LeetCode) 🔧 Approach Used (Monotonic Stack - Greedy): • Used a stack to maintain digits in increasing order • If current digit is smaller than top → pop larger digits (to minimize number) • Continued until k digits are removed • If still k remains, removed from end • Built final number and removed leading zeros 📌 Key Idea: To get the smallest number, always try to remove larger digits that come before smaller digits. ⏳ Complexity: Time: O(n) Space: O(n) 🧠 Key Learning: Greedy + stack works perfectly when we need to build the smallest/largest sequence by removing elements. 💡 Optimization Insight: Monotonic stack helps make optimal decisions locally, leading to a globally optimal solution. 📂 Topics Covered: Stack, Greedy, Strings 📊 Example: Input: "1432219", k = 3 Output: "1219" 🔥 Another powerful use of monotonic stack in optimization problems! #100DaysOfCode #DSA #CPP #LeetCode #CodingJourney #CompetitiveProgramming

🚀 Day 23 of 100 Days LeetCode Challenge Problem: Maximum Non-Negative Product in a Matrix Today’s problem was a deep dive into Dynamic Programming with edge cases (negative values) 🔥 💡 Key Insight: Since the grid contains negative numbers, the product can flip sign. 👉 So at each cell, we must track: Maximum product so far Minimum product so far Because: Negative × Negative = Positive 💥 🔍 Core Approach (DP): 1️⃣ DP State: For each cell (i, j) maintain: maxProduct[i][j] minProduct[i][j] 2️⃣ Transition: From top (i-1, j) and left (i, j-1): Multiply current value with both max & min Take: max → for maxProduct min → for minProduct 3️⃣ Final Answer: If final max ≥ 0 → return max % (10⁹ + 7) Else → return -1 🔥 What I Learned Today: Negative values require tracking both extremes DP is not always just “max”—sometimes it’s min + max together Edge cases define the real difficulty of a problem 📈 Challenge Progress: Day 23/100 ✅ Getting stronger with DP! LeetCode, Dynamic Programming, Matrix, Optimization, Negative Numbers, Algorithms, DSA Practice, Coding Challenge, Problem Solving #100DaysOfCode #LeetCode #DSA #CodingChallenge #DynamicProgramming #Matrix #ProblemSolving #TechJourney #ProgrammerLife #SoftwareDeveloper #CodingLife #LearnToCode #Developers #Consistency #GrowthMindset #InterviewPrep

🚀 Day 19 of 100 Days LeetCode Challenge Problem: Count Submatrices With Equal Frequency of X and Y Today’s problem was a solid combination of 2D Prefix Sum + Hashing concept 🔥 💡 Key Insight: We need submatrices that: Include the top-left cell (0,0) Have equal number of 'X' and 'Y' Contain at least one 'X' 👉 Trick: Convert the grid into values: 'X' → +1 'Y' → -1 '.' → 0 🔍 Core Approach: 1️⃣ 2D Prefix Sum Transformation Build prefix sum based on above conversion 2️⃣ Check Each Submatrix (0,0 → i,j) If sum == 0 → equal number of X and Y ✅ 3️⃣ Extra Condition: Ensure at least one 'X' exists 👉 Track X count separately using another prefix matrix 🔥 What I Learned Today: Transforming problems into numbers simplifies logic Prefix sums + condition checks = powerful combo Always handle extra constraints carefully 📈 Challenge Progress: Day 19/100 ✅ Almost hitting Day 20! LeetCode, Prefix Sum, Matrix, Hashing, Problem Transformation, Algorithms, DSA Practice, Coding Challenge, Problem Solving #100DaysOfCode #LeetCode #DSA #CodingChallenge #PrefixSum #Matrix #Hashing #ProblemSolving #TechJourney #ProgrammerLife #SoftwareDeveloper #CodingLife #LearnToCode #Developers #Consistency #GrowthMindset #InterviewPrep