sdeProblemSheet.md

🚀 SDE Problem Sheet

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[x] denotes problem number x on Leetcode

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📅 Day 1 (Arrays)

• 1️⃣ Find the duplicate in an array of N integers [287]

  • ✅ Leetcode 287
  • ✅ GeeksforGeeks

• 2️⃣ Sort an array of 0’s 1’s 2’s without using extra space or sorting algo [75]

  • ✅ Leetcode 75
  • ✅GeeksforGeeks

• 3️⃣ Repeat and Missing Number [645]

  • ✅ Leetcode 645
  • ✅ GeeksforGeeks

• 4️⃣ Merge two sorted Arrays without extra space [21]

  • ✅ Leetcode 21
  • ✅ GeeksforGeeks
  • ✅ Techiedelight

• 5️⃣ Kadanes Algorithm

  • ✅ Github
  • ✅ GeeksforGeeks

• 6️⃣ Merge Overlapping Subintervals [56]

  • ✅ Leetcode 56
  • ✅ GeeksforGeeks

---

📅 Day 2 (Arrays)

• 1️⃣ Set Matrix Zeros [73]

  • ✅ Leetcode 73
  • ✅ GeeksforGeeks

• 2️⃣ Pascal Triangle [118] [119]

  • ✅ Leetcode 118
  • ✅ Leetcode 119
  • ✅ GeeksforGeeks

• 3️⃣ Next Permutation [31]

  • ✅ Leetcode 31

• 4️⃣ Inversion of Array (Using Merge Sort)

  • ✅ Github
  • ✅ GeeksforGeeks

• 5️⃣ Stock Buy and Sell [121] [122] [123] [309] [188]

  • ✅ Leetcode 121
  • ✅ Leetcode 122
  • ✅ Leetcode 123
  • ✅ Leetcode 309

• 6️⃣ Rotate Matrix [48]

  • ✅ Github

---

📅 Day 3 (Math)

• 1️⃣ Excel Column Number [168] [171]

  • ✅ Leetcode 168
  • ✅ Leetcode 171
  • ✅ GeeksforGeeks

• 2️⃣ Find n^x in log N [50]

  • ✅ Leetcode 50
  • ✅ GeeksforGeeks
  • ✅ GeeksforGeeks

• 3️⃣ Count trailing zeros in factorial of a number [172]

  • ✅ Leetcode 172
  • ✅ GeeksforGeeks

• 4️⃣ Find GCD in Log N

  • ✅ Github
  • ✅ GeeksforGeeks

• 5️⃣ Grid Unique Paths [62]

  • ✅ Leetcode 62
  • ✅ GeeksforGeeks

• 6️⃣ Go through Puzzles from GFG

  • ✅ GeeksforGeeks

---

📅 Day 4 (Hashing)

• 1️⃣ 2 Sum problem [1]

  • ✅ Leetcode 1
  • ✅ GeeksforGeeks

• 2️⃣ 4 Sum problem [18]

  • ✅ Leetcode 18

• 3️⃣ Longest Consecutive Sequence [128]

  • ✅ Leetcode 128
  • ✅ GeeksforGeeks

• 4️⃣ Longest Subarray with 0 sum

  • ✅ GeeksforGeeks

• 5️⃣ Count number of subarrays with given XOR

• 6️⃣ Longest substring without repeat [3]

  • ✅ Leetcode 3
  • ✅ GeeksforGeeks

---

📅 Day 5 (Linked List)

• 1️⃣ Reverse a Linked List [206]

  • ✅ Leetcode 206
  • ✅ GeeksforGeeks

• 2️⃣ Find middle of Linked List [876]

  • ✅ Github
  • ✅ GeeksforGeeks

• 3️⃣ Merge two sorted Linked List [21]

  • ✅ Leetcode 21
  • ✅ GeeksforGeeks

• 4️⃣ Remove N-th node from back of Linked List [19]

  • ✅ Leetcode 19
  • ✅ Leetcode

• 5️⃣ Delete a given Node when a node is given [237]

  • ✅ Leetcode 237

• 6️⃣ Add two numbers as Linked List [2]

  • ✅ Leetcode 2

---

📅 Day 6 (Linked List)

• 1️⃣ Find intersection point of Y Linked List [160]

  • ✅ Leetcode 160

• 2️⃣ Check if a Linked List is palindrome or not [234]

  • ✅ Leetcode 234
  • ✅ GeeksforGeeks

• 3️⃣ Reverse a Linked List in groups [25]

  • ✅ Leetcode 25
  • ✅ Github

• 4️⃣ Detect a cycle and removing loop [141] [142]

  • ✅ Leetcode 141
  • ✅ Leetcode 142

• 5️⃣ Flattening of a Linked List [430]

  • ✅ Leetcode 430

• 6️⃣ Rotate a Linked List [61]

  • ✅ Leetcode 61

• 7️⃣ Clone a Linked List with random and next pointer. [138]

  • ✅ Leetcode 138

---

📅 Day 7 (Pointers)

• 1️⃣ Merge two sorted Linked Lists [21]

  • ✅ Leetcode 21

• 2️⃣ Find the starting point of the loop [142]

  • ✅ Leetcode 142

• 3️⃣ 3 sum [15]

  • ✅ Leetcode 15

• 4️⃣ Trapping rainwater [42]

  • ✅ Leetcode 42

• 5️⃣ Remove Duplicate from Sorted array [26]

  • ✅ Leetcode 26

• 6️⃣ Max continuous number of 1’s [485] [1446]

  • ✅ Leetcode 485
  • ✅ Leetcode 1446

---

📅 Day 8 (Greedy)

• 1️⃣ N meeting in one room [435]

  • ✅ Leetcode 435
  • ✅ GeeksforGeeks

• 2️⃣ Activity Selection

  • ✅ GeeksforGeeks ( Similar to N meeting in one room )

• 3️⃣ Greedy algorithm to find minimum number of coins [322]

  • ✅ GeeksforGeeks ( greedy won’t work )
  • ✅ Leetcode 322 ( dp approach )

• 4️⃣ Fractional Knapsack Problem

  • ✅ GeeksforGeeks

• 5️⃣ Minimum number of platforms required for a railway

  • ✅ GeeksforGeeks
  • ✅ GeeksforGeeks

• 6️⃣ Job sequencing Problem

  • ✅ GeeksforGeeks

---

📅 Day 9 (Backtracking)

• 1️⃣ N queens Problem

  • ✅ Github
  • ✅ Github
  • ✅ GeeksforGeeks

• 2️⃣ Sudoko

  • ✅ Github
  • ✅ GeeksforGeeks

• 3️⃣ M coloring Problem

  • ✅ Github
  • ✅ GeeksforGeeks

• 4️⃣ Rat in a Maze

  • ✅ Github
  • ✅ GeeksforGeeks

• 5️⃣ Print all Permutations of a string/array

• 6️⃣ Word Break (print all ways)

---

📅 Day 10 (Backtracking)

• 1️⃣ Combination sum-1 [39] [216]

  • ✅ Leetcode 39

  • ✅ Leetcode 216

• 2️⃣ Combination sum-2 [40]

  • ✅ Leetcode 40

• 3️⃣ Palindrome Partioning

• 4️⃣ Subset Sum-1 [416]

  • ✅ leet 416

• 5️⃣ Subset Sum-2

• 6️⃣ K-th permutation Sequence

---

📅 Day 11 (Divide and Conquer)

• 1️⃣ 1/N-th root of an integer (use binary search)

  • ✅ GeeksforGeeks

• 2️⃣ Matrix Median

• 3️⃣ Find the element that appears once in sorted array, and rest element appears twice (Binary search)

  • ✅ GeeksforGeeks

• 4️⃣ Search element in a sorted and rotated array

  • ✅ Github ( Find pivot by searching the smallest elements index , then apply BS )
  • ✅ GeeksforGeeks

• 5️⃣ K-th element of two sorted arrays

• 6️⃣ Median of an array

  • ✅ GeeksforGeeks

---

📅 Day 12 (Bit Manipulation)

• 1️⃣ Check if a number if a power of 2 or not in O(1) [231]

  • ✅ Github

• 2️⃣ Count total set bits [338]

  • ✅ Leetcode 338

• 3️⃣ Divide Integers without / operator [29]

  • ✅ GeeksforGeeks
  • ✅ Leetcode 29

• 4️⃣ Power Set

  • ✅ Github

• 5️⃣ Find MSB in O(1)

  • ✅ Github
  • ✅ GeeksforGeeks

• 6️⃣ Find square of a number without using multiplication or division operators

  • ✅ GeeksforGeeks

---

📅 Day 13 (Stack and Queue)

• 1️⃣ Implement Stack / Implement Queue

  • ✅ GeeksforGeeks
  • ✅ GeeksforGeeks

• 2️⃣ BFS

  • ✅ GeeksforGeeks

• 3️⃣ Implement Stack using Queue

  • ✅ Leetcode 225

  • ✅ GeeksforGeeks

• 4️⃣ Implement Queue using Stack

  • ✅ GeeksforGeeks

• 5️⃣ Check for balanced parentheses

  • ✅ GeeksforGeeks
  • ✅ GeeksforGeeks

• 6️⃣ Next Greater Element

  • ✅ GeeksforGeeks

---

📅 Day 14 (Stack and Queue)

• 1️⃣ Next Smaller Element

  • ✅ GeeksforGeeks ( approach similar to NGE )

• 2️⃣ LRU cache [146]

  • ✅ Leetcode 146
  • ✅ GeeksforGeeks

• 3️⃣ Largest rectangle in histogram

  • ✅ Github
  • ✅ GeeksforGeeks

• 4️⃣ Sliding Window maximum [239]

  • ✅ Leetcode 239
  • ✅ GeeksforGeeks

• 5️⃣ Implement Min Stack

  • ✅ Github
  • ✅ Github
  • ✅ GeeksforGeeks

• 6️⃣ Rotten Orange (Using BFS)

  • ✅ GeeksforGeeks
  • ✅ Github

---

📅 Day 15 (String)

• 1️⃣ Reverse Words in a String

  • ✅ GeeksforGeeks
  • ✅ GeeksforGeeks
  • ✅ GeeksforGeeks

• 2️⃣ Longest Palindrome in a string [5]

  • ✅ Leetcode 5
  • ✅ GeeksforGeeks

• 3️⃣ Roman Number to Integer and vice versa [12][13]

  • ✅ Leetcode 13
  • ✅ Leetcode 12

• 4️⃣ Implement ATOI/STRSTR

  • ✅ GeeksforGeeks
  • ✅ GeeksforGeeks

• 5️⃣ Longest Common Prefix [14]

  • ✅ Leetcode 14
  • ✅ GeeksforGeeks
  • ✅ GeeksforGeeks
  • ✅ GeeksforGeeks

• 6️⃣ Rabin Karp

  • ✅ Github
  • ✅ GeeksforGeeks

---

📅 Day 16 (String)

• 1️⃣ Prefix Function/Z-Function

  • ✅ Github
  • ✅ GeeksforGeeks
  • ✅ YouTube

• 2️⃣ KMP Algorithm

  • ✅ Github
  • ✅ GeeksforGeeks

• 3️⃣ Minimum characters needed to be inserted in the beginning to make it palindromic

  • ✅ Github
  • ✅ GeeksforGeeks

• 4️⃣ Check for Anagrams [242] [1347] [438] [49]

  • ✅ Leetcode 242
  • ✅ Leetcode 1347
  • ✅ Leetcode 438
  • ✅ Leetcode 49

• 5️⃣ Count and Say [38]

  • ✅ Leetcode 38

• 6️⃣ Compare version numbers [165]

  • ✅ Leetcode 165

---

📅 Day 17 (Binary Tree)

• 1️⃣ Inorder Traversal [94]

  • ✅ Github
  • ✅ Github

• 2️⃣ Preorder Traversal [144]

  • ✅ Github
  • ✅ Github

• 3️⃣ Postorder Traversal [145]

  • ✅ Github
  • ✅ Github
  • ✅ Github

• 4️⃣ Left View Of Binary Tree

  • ✅ Github
  • ✅ Github

• 5️⃣ Bottom View of Binary Tree

  • ✅ Github

• 6️⃣ Top View of Binary Tree

  • ✅ Github

---

📅 Day 18 (Binary Tree)

• 1️⃣ Level order Traversal / Level order traversal in spiral form [102] [103]

  • ✅ Github
  • ✅ Leetcode 103

• 2️⃣ Height of a Binary Tree [104]

  • ✅ Leetcode 104

• 3️⃣ Diameter of Binary Tree [543]

  • ✅ Leetcode 543

• 4️⃣ Check if Binary tree is height balanced or not [110]

  • ✅ Leetcode 110

• 5️⃣ LCA in Binary Tree [236]

  • ✅ Leetcode 236

• 6️⃣ Check if two trees are identical or not [100]

  • ✅ Leetcode 100

---

📅 Day 19 (Binary Tree)

• 1️⃣ Maximum path sum [124]

  • ✅ Leetcode 124

• 2️⃣ Construct Binary Tree from inorder and preorder [105]

  • ✅ Leetcode 105

• 3️⃣ Construct Binary Tree from Inorder and Postorder [106]

  • ✅ Leetcode 106

• 4️⃣ Symmetric Binary Tree [101]

  • ✅ Leetcode 101

• 5️⃣ Flatten Binary Tree to Linked List [114]

  • ✅ Leetcode 114

• 6️⃣ Check if Binary Tree is mirror of itself or not [101]

  • ✅ Leetcode 101

---

📅 Day 20 (Binary Search Tree)

• 1️⃣ Populate Next Right pointers of Tree [116]

  • ✅ Leetcode 116

• 2️⃣ Search given Key in BST [700]

  • ✅ Leetcode 700

• 3️⃣ Construct BST from given keys [108]

  • ✅ Leetcode 108

• 4️⃣ Check is a BT is BST or not [98]

  • ✅ Leetcode 98

• 5️⃣ Find LCA of two nodes in BST [235]

  • ✅ Leetcode 235

• 6️⃣ Find the inorder predecessor/successor of a given Key in BST

  • ✅ git tree pre_suc
  • ✅ GeeksforGeeks

---

📅 Day 21 (Binary Search Tree)

• 1️⃣ Floor and Ceil in a BST

  • ✅ Github

• 2️⃣ Find K-th smallest and K-th largest element in BST [230]

  • ✅ git leet 230
  • ✅ git tree kth lathe
  • ✅ GeeksforGeeks

• 3️⃣ Find a pair with a given sum in BST [653]

  • ✅ git leet 653

• 4️⃣ BST iterator [173]

  • ✅ git leet 173

• 5️⃣ Size of the largest BST in a Binary Tree

  • ✅ gitb tree largest bst in bt
  • ✅ GeeksforGeeks

• 6️⃣ Serialize and deserialize Binary Tree [297]

  • ✅ git 297

---

📅 Day 22 (Mixed Questions)

• 1️⃣ Binary Tree to Double Linked List [114] [430]

  • ✅ Leetcode 114
  • ✅ Leetcode 430
  • ✅ Github

• 2️⃣ Find median in a stream of running integers [295]

  • ✅ Leetcode 295

• 3️⃣ K-th largest element in a stream [703]

  • ✅ Leetcode 703

• 4️⃣ Distinct numbers in Window

  • ✅ Github

• 5️⃣ K-th largest element in an unsorted array [215]

  • ✅ Leetcode 215

• 6️⃣ Flood-fill Algorithm [733]

  • ✅ Leetcode 733

---

📅 Day 23 (Graph)

• 1️⃣ Clone a graph [133]

  • ✅ Leetcode 133
  • ✅ Github

• 2️⃣ DFS

  • ✅ Github

• 3️⃣ BFS

  • ✅ Github

• 4️⃣ Detect A cycle in Undirected Graph/Directed Graph

  • ✅ Github
  • ✅ Github
  • ✅ Github

• 5️⃣ Topological Sort

  • ✅ Github
  • ✅ GeeksforGeeks

• 6️⃣ Number of islands [200]

  • ✅ Github

• 7️⃣ Bipartite Check [785]

  • ✅ Leetcode 785
  • ✅ Github

---

📅 Day 24 (Graph)

• 1️⃣ SCC(using KosaRaju’s Algorithm)

  • ✅ Github
  • ✅ GeeksforGeeks

• 2️⃣ Djisktra’s Algorithm [743]

  • ✅ Github
  • ✅ Leetcode 743

• 3️⃣ Bellman Ford Algorithm

  • ✅ Github

• 4️⃣ Floyd Warshall Algorithm

  • ✅ Github

• 5️⃣ MST using Prim’s Algorithm

  • ✅ Github

• 6️⃣ MST using Kruskal’s Algorithm

  • ✅ Github

---

📅 Day 25 (Dynamic Programming)

• 1️⃣ Max Product Subarray [152]

  • ✅ Leetcode 152
  • ✅ GeeksforGeeks

• 2️⃣ Longest Increasing Subsequence [300]

  • ✅ Leetcode 300

• 3️⃣ Longest Common Subsequence [1143]

  • ✅ Github
  • ✅ Github

• 4️⃣ 0-1 Knapsack

  • ✅ Github
  • ✅ Github

• 5️⃣ Edit Distance [72]

  • ✅ Leetcode 72
  • ✅ GeeksforGeeks

• 6️⃣ Maximum sum increasing subsequence

  • ✅ Github

• 7️⃣ Matrix Chain Multiplication

  • ✅ Github
  • ✅ Github

---

📅 Day 26 (Dynamic Programming)

• 1️⃣ Maximum sum path in matrix, (count paths, and similar type do, also backtrack to find the maximum path) [64]

  • ✅ Leetcode 64
  • ✅ Github

• 2️⃣ Coin change [322]

  • ✅ Github
  • ✅ Github

• 3️⃣ Subset Sum [416]

  • ✅ Github
  • ✅ Github
  • ✅ Github
  • ✅ Github

• 4️⃣ Rod Cutting

  • ✅ Github

• 5️⃣ Egg Dropping [887]

  • ✅ Github
  • ✅ Github

• 6️⃣ Word Break [139]

• 7️⃣ Palindrome Partitioning

  • ✅ Github

---

📅 Day 27

• 1️⃣ Revise OS notes that you would have made during your sem

• 2️⃣ If not made notes, spend 2 or 3 days and make notes from Knowledge Gate

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📅 Day 28

• 1️⃣ Revise DBMS notes that you would have made during your semester

• 2️⃣ If not made notes, spend 2 or 3 days and make notes from Knowledge Gate.

---

📅 Day 29

• 1️⃣ Revise CN notes, that you would have made during your sem.

• 2️⃣ If not made notes, spend 2 or 3 days and make notes from Knowledge Gate.

---

📅 Day 30

• 1️⃣ Make a note of how will your represent your projects, and prepare all questions related to tech which you have used in your projects. Prepare a note which you can say for 3-10 minutes when he asks you that say something about the project

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🚀 Hurrah!! You are ready for your placement after a month of hard-work without a cheat day.