Hi, I'm an undergraduate student and here is the "Must Do list of questions" that I had used for my preparation and you should check out as well for the preparation of Interviews at any of the Tech giants. The questions listed are pretty common and their descriptions are just one search away. This list has the minimum and the most important set of questions for each type of Interview Question Pattern.
I would suggest to solve these questions in a Breadth-First fashion covering each pattern one by one. This approach worked for me because it helps in covering all the patterns simultaneously.
Best of luck !!!

Arrays :

1. Subarray with given sum
2. Kadane’s Algorithm
3. Missing number in array
4. Merge two sorted arrays
5. Rearrange array alternatively
6. Number of pairs
7. Inversion of Array
8. Sort an array of 0s, 1s and 2s
9. Equilibrium point in array
10. Leaders in an array
11. Minimum Platforms
12. Reverse array in groups
13. K’th smallest element
14. Trapping Rain Water
15. Pythagorean Triplet
16. Chocolate Distribution Problem
17. Stock buy and sell
18. Element with left side smaller and right side greater
19. Convert array into Zig-Zag fashion
20. Last Index of 1
21. Spirally traversing a matrix
22. Largest Number formed from an Array

String :

1. Reverse words in a given string
2. Permutations of a given string
3. Longest Palindrome in a String
4. Recursively remove all adjacent duplicates
5. Check if string is rotated by two places
6. Roman Number to Integer
7. Anagram
8. Remove Duplicates
9. Form a Palindrome
10. Longest Distinct Characters in the string
11. Implement Atoi
12. Implement strstr
13. Longest Common Prefix

Linked List :

1. Finding middle element in a linked list
2. Reverse a linked list
3. Rotate a Linked List
4. Reverse a Linked List in groups of given size
5. Intersection point in Y shaped linked lists
6. Detect Loop in linked list
7. Remove loop in Linked List
8. n’th node from end of linked list
9. Flattening a Linked List
10. Merge two sorted linked lists
11. Intersection point of two Linked Lists
12. Pairwise swap of a linked list
13. Add two numbers represented by linked lists
14. Check if Linked List is Palindrome
15. Implement Queue using Linked List
16. Implement Stack using Linked List
17. Given a linked list of 0s, 1s and 2s, sort it
18. Delete without head pointer

Stack and Queue :

1. Parenthesis Checker
2. Next larger element
3. Queue using two Stacks
4. Stack using two queues
5. Get minimum element from stack
6. LRU Cache
7. Circular tour
8. First non-repeating character in a stream
9. Rotten Oranges
10. Maximum of all subarrays of size k

Tree :

1. Print Left View of Binary Tree
2. Check for BST
3. Print Bottom View of Binary Tree
4. Print a Binary Tree in Vertical Order
5. Level order traversal in spiral form
6. Connect Nodes at Same Level
7. Lowest Common Ancestor in a BST
8. Convert a given Binary Tree to Doubly Linked List
9. Write Code to Determine if Two Trees are Identical or Not
10. Given a binary tree, check whether it is a mirror of itself
11. Height of Binary Tree
12. Maximum Path Sum
13. Diameter of a Binary Tree
14. Number of leaf nodes
15. Check if given Binary Tree is Height Balanced or Not
16. Serialize and Deserialize a Binary Tree

Heap :

1. Find median in a stream
2. Heap Sort
3. Operations on Binary Min Heap
4. Rearrange characters
5. Kth largest element in a stream
6. Merge K sorted linked lists
7. Kth largest element in a stream

Recursion :

1. Flood fill Algorithm
2. Number of paths in matrix
3. Combination Sum
4. Josephus problem

Hashing :

1. Relative Sorting
2. Sorting Elements of an Array by Frequency
3. Largest subarray with 0 sum
4. Common elements
5. Find all four sum numbers
6. Swapping pairs make sum equal
7. Count distinct elements in every window
8. Array Pair Sum Divisibility Problem
9. Longest consecutive subsequence
10. Array Subset of another array
11. Find all pairs with a given sum
12. Find first repeated character
13. Zero Sum Subarrays
14. Minimum indexed character
15. Check if two arrays are equal or not
16. Uncommon characters
17. Smallest window in a string containing all the characters of another string
18. First element to occur k times
19. Check if frequencies can be equal

Graph :

1. Depth First Traversal
2. Breadth First Traversal
3. Detect cycle in undirected graph
4. Detect cycle in a directed graph
5. Topological sort
6. Find the number of islands
7. Implementing Dijkstra
8. Minimum Swaps
9. Strongly Connected Components
10. Shortest Source to Destination Path
11. Find whether path exist
12. Minimum Cost Path
13. Circle of Strings
14. Floyd Warshall
15. Alien Dictionary
16. Snake and Ladder Problem

Greedy :

1. Activity Selection
2. N meetings in one room
3. Coin Piles
4. Maximize Toys
5. Page Faults in LRU
6. Largest number possible
7. Minimize the heights
8. Minimize the sum of product
9. Huffman Decoding
10. Minimum Spanning Tree
11. Shop in Candy Store
12. Geek collects the balls

Dynamic Programming :

1. Minimum Operations
2. Max length chain
3. Minimum number of Coins
4. Longest Common Substring
5. Longest Increasing Subsequence
6. Longest Common Subsequence
7. 0 – 1 Knapsack Problem
8. Maximum sum increasing subsequence
9. Minimum number of jumps
10. Edit Distance
11. Coin Change Problem
12. Subset Sum Problem
13. Box Stacking
14. Rod Cutting
15. Path in Matrix
16. Minimum sum partition
17. Count number of ways to cover a distance
18. Egg Dropping Puzzle
19. Optimal Strategy for a Game
20. Shortest Common Supersequence

Divide and Conquer :

1. Find the element that appears once in sorted array
2. Search in a Rotated Array
3. Binary Search
4. Sum of Middle Elements of two sorted arrays
5. Quick Sort
6. Merge Sort
7. K-th element of two sorted Arrays

Backtracking :

1. N-Queen Problem
2. Solve the Sudoku
3. Rat in a Maze Problem
4. Word Boggle
5. Generate IP Addresses

Bit Magic :

1. Find first set bit
2. Rightmost different bit
3. Check whether K-th bit is set or not
4. Toggle bits given range
5. Set kth bit
6. Power of 2
7. Bit Difference
8. Rotate Bits
9. Swap all odd and even bits
10. Count total set bits
11. Longest Consecutive 1’s
12. Sparse Number
13. Alone in a couple
14. Maximum subset XOR

Credits - GfG