Solved Combination Sum II problem using recursion and backtracking in C++.

📅 Day 41 of #100DaysOfCode Problem: Merge k Sorted Lists (LeetCode 23) This one was all about optimization and clean recursion. Instead of merging lists one by one, I used a divide and conquer approach merge them in pairs, just like merge sort. Approach: 1️⃣ If there’s only one list, return it - base case. 2️⃣ Split the range of lists into two halves using recursion. 3️⃣ Merge both halves using a helper function that merges two sorted lists. 4️⃣ Keep dividing until everything is combined into one sorted list. #100DaysOfCode #LeetCode #DSA #Cplusplus #ProblemSolving #DivideAndConquer #Recursion #CodingChallenge #Algorithms #Programming #CodeNewbie #DeveloperLife #LearningInPublic #KeepLearning #SoftwareEngineering #TechCommunity #DailyDSA #GrowthMindset #Motivation

📅 Day 46 of #100DaysOfCode Problem: Combinations (LeetCode 77) Approach: 1️⃣ Used recursion to build combinations incrementally. 2️⃣ For every number, we have two choices — include it or skip it. 3️⃣ Once we’ve picked k numbers, added that combination to the result. 4️⃣ Used backtracking (pop_back) to explore the next possibility cleanly. #100DaysOfCode #LeetCode #DSA #Backtracking #Recursion #ProblemSolving #Cplusplus #CodingChallenge #Algorithms #Programming #DeveloperLife #CodeNewbie #SoftwareEngineering #CodingJourney #DailyDSA #KeepLearning #GrowthMindset #Motivation #TechCommunity

📅 Day 28 of #100DaysOfCode 🚀 Problem: 49. Group Anagrams (LeetCode) Approach: -> For each string, sort its characters — the sorted version acts as a unique key for its anagram group. -> Store all words with the same sorted key inside a hash map (unordered_map<string, vector<string>>). -> After processing all words, collect all grouped values from the map into a result vector. ->This leverages hashing + sorting for efficient grouping — O(n * k log k) where k is average string length. #100DaysOfCode #LeetCode #DSA #ProblemSolving #Cplusplus #CodingChallenge #Algorithms #DataStructures #Hashing #StringManipulation #CodingCommunity #Programming #DeveloperLife #LearnToCode #TechCommunity #DailyDSA #CodeNewbie #SoftwareEngineering #CodingJourney #Consistency #KeepLearning #LearningInPublic #GrowthMindset #Motivation

📅 Day 35 of #100DaysOfCode Problem: Search in Rotated Sorted Array II (LeetCode 81) Approach: 1️⃣ First, handled duplicates by skipping consecutive equal elements from both ends to avoid confusion while finding the rotation point. 2️⃣ Used a modified binary search to find the pivot (the smallest element’s index) — this separates the rotated parts of the array. 3️⃣ Performed binary search on both halves — before and after the pivot — to check where the target lies. 4️⃣ Returned true if found in either part, else false. #100DaysOfCode #LeetCode #BinarySearch #RotatedArray #ProblemSolving #Algorithms #DSA #Cplusplus #CodingChallenge #Programming #DeveloperLife #CodeNewbie #DailyDSA #TechCommunity #KeepLearning #SoftwareEngineering #LearningInPublic #Motivation

📅 Day 42 of #100DaysOfCode Problem: Subsets (LeetCode 78) Approach: 1️⃣ Used backtracking to explore every possibility — either include the current element or skip it. 2️⃣ When the index reaches the end, added the current subset to the result. 3️⃣ Backtracked properly to remove elements before exploring the next choice. 4️⃣ This ensures every possible combination is covered without duplicates. #100DaysOfCode #LeetCode #Backtracking #Recursion #DSA #Cplusplus #ProblemSolving #CodingChallenge #Algorithms #Programming #DeveloperLife #CodeNewbie #DailyDSA #TechCommunity #KeepLearning #GrowthMindset #SoftwareEngineering #LearningInPublic #Motivation

📅 Day 48 of #100DaysOfCode Problem: Search in Rotated Sorted Array II (LeetCode 81) Approach: 1️⃣ First, used a pivot function to find the smallest element’s index, skipping duplicate values on both sides. 2️⃣ Once the pivot was found, split the array into two sorted parts. 3️⃣ Applied normal binary search on both halves to find the target. 4️⃣ Combined both steps to handle rotations and duplicates efficiently. #100DaysOfCode #LeetCode #DSA #ProblemSolving #BinarySearch #Cplusplus #CodingChallenge #Algorithms #Programming #DeveloperLife #CodeNewbie #SoftwareEngineering #CodingJourney #DailyDSA #KeepLearning #TechCommunity #GrowthMindset #Motivation

📅 Day 31 of #100DaysOfCode Problem: Reverse Pairs (LeetCode 493) Approach: 1️⃣ Divide the array using merge sort to count pairs efficiently. 2️⃣ Count cross-pairs where nums[i] > 2 * nums[j] while merging. 3️⃣ Merge the halves back in sorted order to maintain correct comparisons. 4️⃣ Sum up counts from left, right, and cross halves for the final result. #100DaysOfCode #LeetCode #DSA #ProblemSolving #Cplusplus #CodingChallenge #Algorithms #Programming #DeveloperLife #CodeNewbie #DailyDSA #SoftwareEngineering #CodingJourney #LearningInPublic #TechCommunity #KeepLearning #DivideAndConquer #GrowthMindset #Motivation

📅 Day 36 of #100DaysOfCode Today’s challenge was one of the most interesting and tricky recursion problems! Problem: Regular Expression Matching (LeetCode #10) 🔍 Approach: The goal is to determine if a given string text matches a pattern that includes: . → Matches any single character * → Matches zero or more occurrences of the preceding element 1️⃣ Used recursion to check character-by-character matches. 2️⃣ For each step: Checked if the current characters match (text[0] == pattern[0] or pattern[0] == '.'). If the next pattern character is *, explored two possibilities: Skip * and the previous character (zero occurrence). Use * to match one or more occurrences (consume one character from text). 3️⃣ Continued recursively until the entire text and pattern were checked. #100DaysOfCode #LeetCode #DSA #ProblemSolving #Cplusplus #CodingChallenge #Algorithms #Programming #DeveloperLife #CodeNewbie #DailyDSA #SoftwareEngineering #CodingJourney #LearningInPublic #TechCommunity #KeepLearning #Recursion #GrowthMindset #Motivation

📅 Day 50 of #100DaysOfCode Problem: Simplify Path (LeetCode 71) Approach: 1️⃣ Used a stringstream to split the path by '/'. 2️⃣ Ignored empty tokens and "." since they don’t change the directory. 3️⃣ For "..", popped the last directory from the stack (if any). 4️⃣ Rebuilt the canonical path from the stack in the correct order. #100DaysOfCode #LeetCode #DSA #ProblemSolving #Stacks #Cplusplus #CodingChallenge #Algorithms #Programming #DeveloperLife #CodingJourney #CodeNewbie #DailyDSA #SoftwareEngineering #KeepLearning #GrowthMindset #Motivation #TechCommunity #CleanCode

📅 Day 44 of #100DaysOfCode Problem: Minimum Number of Operations to Make Array Continuous (LeetCode 2009) Approach: 1️⃣ For each element, assumed it to be the starting point of the range. 2️⃣ Calculated what the range should end at → start + n - 1. 3️⃣ Iterated over all numbers, counted how many don’t fit in this range (those need to be replaced). 4️⃣ Kept track of the minimum replacements across all possible ranges. #100DaysOfCode #LeetCode #DSA #ProblemSolving #Cplusplus #Algorithms #CodingChallenge #Programming #DeveloperLife #CodeNewbie #DailyDSA #SoftwareEngineering #CodingJourney #TechCommunity #KeepLearning #GrowthMindset #Motivation #LearningInPublic