30 Days Interview Preparation Plan for Freshers🎯

 30 Days Interview Preparation Plan for Freshers[2022]🎯

Day1: (Arrays)

1. Sort an array of 0’s 1’s 2’s without using extra space or sorting algo
2. Repeat and Missing Number
3. Merge two sorted Arrays without extra space
4. Kadane’s Algorithm
5. Merge Overlapping Subintervals
6. Find the duplicate in an array of N+1 integers.

Day2: (Arrays)

1. Set Matrix Zeros
2. Pascal Triangle
3. Next Permutation
4. Inversion of Array (Using Merge Sort)
5. Stock Buy and Sell
6. Ro tate Matrix

Day3: (Arrays/maths)

1. Search in a 2D matrix
2. Pow(X,n)
3. Majority Element (>N/2 times)
4. Majority Element (>N/3 times)
5. Grid Unique Paths
6. Reverse Pairs (Leetcode)
7. Go through Puzzles from GFG** (Search on own)

Day4: (Hashing)

1. 2 Sum problem
2. 4 Sum problem
3. Longest Consecutive Sequence
4. Largest Subarray with 0 sum
5. Count number of subarrays with given XOR (this clearsa lot of problems)
6. Longest substring without repeat

Day5: (LinkedList)

1. Reverse a LinkedList
2. Find middle of LinkedList
3. Merge two sorted Linked List
4. Remove N-th node from back of LinkedList
5. Delete a given Node when a node is given. (0(1) solution)
6. Add two numbers as LinkedList

Day6: (Linked List)

1. Find intersection point of Y LinkedList
2. Detect a cycle in Linked List
3. Reverse a LinkedList in groups of size k
4. Check if a LinkedList is palindrome or not.
5. Find the starting point of the Loop of LinkedList
6. Flattening of a LinkedList**
7. Rotate a LinkedList

Day7: (2-pointer)

1. Clone a Linked List with random and next pointer
2. 3 sum
3. Trapping rainwater
4. Remove Duplicate from Sorted array
5. Max consecutive ones

Day8: (Greedy)

1. N meeting in one room
2. Minimum number of platforms required for a railway
3. Job sequencing Problem
4. Fractional Knapsack Problem
5. Greedy algorithm to find minimum number of coins
6. Activity Selection
7. s same as N meeting in one room)

Day9: (Recursion):

1. Subset Sums
2. Subset-II
3. Combination sum-
4. Combination sum
5. Palindrome Partitioning
6. K-th permutation Sequence

Day10: (Recursion and Backtracking)

1. Print all Permutations of a string/array
2. N queens Problem
3. SudokuSolver
4. M coloring Problem
5. Rat in a Maze
6. Word Break -> print all ways

Day11 : (Binary Search)

1. N-th root of an integer (use binary search) (square root, cube root, ..)
2. Matrix Median
3. Find the element that appears once in sorted array, and rest element appears twice (Binary search)
4. Search element in a sorted and rotated array/ find pivot where it is rotated
5. Median of 2 sorted arrays
6. K-th element of two sorted arrays
7. Allocate Minimum Number of Pages
8. Aggressive Cows

Day12: (Bits Manipulation)

1. Check if a number if a power of 2 or not in O(1)
2. Count total set bits
3. Divide Integers without / operator
4. Power Set (this is very important)
5. Find MSB in o(1)
6. Find square of a number without using multiplication or division operators.

Day13: (Stack and Queue)

1. Implement Stack Using Arrays
2. Implement Queue Using Arrays
3. Implement Stack using Queue (using single queue)
4. Implement Queue using Stack (0(1) amortised method)
5. Check for balanced parentheses
6. Next Greater Element
7. Sort a Stack

Day14: (Stack and Queue)

1. Next Smaller Element
2. LRU cache (vvvv. imp)
3. LFU Cache (Hard, can be ignored)
4. Largest rectangle in histogram (Do the one pass solution)
5. Sliding Window maximum
6. Implement Min Stack
7. Rotten Orange (Using BFS)
8. Stock Span Problem
9. Find maximum of minimums of every window size
10. The Celebrity Problem

Day15: (String)

1. Reverse Words in a String
2. Longest Palindrome in a string
3. Roman Number to Integer and vice versa
4. Implement ATOI/STRSTR
5. Longest Common Prefix
6. Rabin Karp

Day16: (String)

1. Prefix Function/Z-Function
2. KMP algo / LPS(pi) array
3. Minimum characters needed to be inserted in the beginning to make it palindromic.
4. Check for Anagrams
5. Count and Say
6. Compare version numbers

Day17: (Binary Tree)

1. Inorder Traversal (with recursion and without recursion)
2. Preorder Traversal (with recursion and without recursion)
3. Postorder Traversal (with recursion and without recursion)
4. LeftView Of Binary Tree
5. Bottom View of Binary Tree
6. Top View of Binary Tree

Day18: (Binary Tree)

1. Level order Traversal / Level order traversal in spiral form
2. Height of a Binary Tree
3. Diameter of Binary Tree
4. Check if Binary tree is height balanced or not
5. LCA in Binary Tree
6. Check if two trees are identical or not

Day 19: (Binary Tree)

1. Maximum path sum
2. Construct Binary Tree from inorder and preorder
3. Construct Binary Tree from Inorder and Postorder
4. Symmetric Binary Tree
5. Flatten Binary Tree to LinkedList
6. Check if Binary Tree is mirror of itself or not

Day 20: (Binary Search Tree)

1. Populate Next Right pointers of Tree
2. Search given Key in BST
3. Construct BST from given keys.
4. Check is a BT is BST or not
5. Find LCA of two nodes in BST
6. Find the inorder predecessor/successor of a given Key in BST.

Day21: (Binary Search Tree)

1. Floor and Ceil in a BST
2. Find K-th smallest and K-th largest element in BST (2 different Questions)
3. Find a pair with a given sum in BST
4. BST iterator
5. Size of the largest BST in a Binary Tree
6. Serialize and deserialize Binary Tree

Day22: (Mixed Questions)

1. Binary Tree to Double Linked List
2. Find median in a stream of running integers.
3. K-th largest element in a stream.
4. Distinct numbers in Window.
5. K-th largest element in an unsorted array.
6. Flood-fill Algorithm

Day23: (Graph)

1. Clone a graph (Not that easy as it looks)
2. DFS
3. BFS
4. Detect A cycle in Undirected Graph/Directed Graph
5. Topo Sort
6. Number of islands (Do in Grid and Graph both)
7. Bipartite Check

Day24: (Graph)

1. SCC(using Kosa Raju’s algo)
2. Djisktra’s Algorithm
3. Bellman Ford Algo
4. Floyd Warshall Algorithm
5. MST using Prim’s Algo
6. MST using Kruskal’s Algo

Day25: (Dynamic Programming)

1. Max Product Subarray
2. Longest Increasing Subsequence
3. Longest Common Subsequence
4. 0–1 Knapsack
5. Edit Distance
6. Maximum sum increasing subsequence
7. Matrix Chain Multiplication

Day26: (DP)

1. Maximum sum path in matrix, (count paths, and similar type do, also backtrack to find
   the maximum path)
2. Coin change
3. Subset Sum
4. Rod Cutting
5. Egg Dropping
6. Word Break
7. Palindrome Partitioning (MCM Variation)
8. Maximum profit in Job scheduling

Day27:

1. Revise OS notes that you would have made during your sem.
2. If not made notes, spend 2 or 3 days and make notes from KnowledgeGate.

Day28:

1. Revise DBMS notes that you would have made during your semesters.
2. If not made notes, spend 2 or 3 days and make notes from Knowledge Gate.

Day29:

1. Revise CN notes, that you would have made during your sem.
2. If not made notes, spend 2 or 3 days and make notes from Knowledge Gate.

Day30:

1. 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.

The above list was prepared by Raj Vikramaditya. I have documented that sheet here.

https://github.com/SamirPaul1/DSAlgo/tree/main/30-Days-SDE-Sheet-Practice