- Arrays
- Trees
- Linked List
- Stack
- Queue
- Dynamic Programming
- Greedy Problems
- Divide and Conquer
- Bit Manipulation
- Mathematical
- Hashing
- String
- Pattern Matching
- Heaps
- Back Tracking
- Graphs
- Workouts
- A -> Linear Search
- B -> Binary Search
- C -> Find a pair in an array whose sum is equal to given number (Hash Approach) - Brute Force, Quick Sort and search complement, Hash Table
- D -> Element that occurs more than n/2 times - Unsorted - Moore's Voting Algorithm, but using quick sort followed by count [or] HashMap
- E -> Element that occurs more than n/2 times - Sorted
- F -> Largest Difference such that the smaller number appears before larger number
- G -> Largest Difference such that the smaller number appears before larger number - Less space complexity
- H -> Largest Difference such that the smaller number appears before larger number - Min So Far
- I -> Find the number occurring odd number of times in the given array(Only one element occurs odd number of times)
- J -> Separate 0's and 1's in an array
- K -> Separate Even and Odd numbers in an array
- L -> 2 elements whose sum is close to zero - either positive or negative
- M -> 3 elements such that their sum is equal to x.
- N -> Find the Equilibrium Index .i.e., left sum and right sum of index should be equal.
- O -> Find the Equilibrium Index .i.e., left sum and right sum of index should be equal - Less Space Complexity.
- P -> Array of unknown size. 0s followed by 1s find the first index of 1
- Q -> Maximum of every contiguous sub-array of size k. - Sliding Window.
- R -> count the no.of smaller elements to the right of each element in the array.
- S -> Largest Multiple of 3 with given digits.
- T -> Sub Array Sum equal to x
- U -> Find Sub Array whose sum is equals zero
- V -> Largest sub array with equal no.of zeros and ones
- W -> Construct a product array such that the ith element in product array contains the product of all the remaining elements but i (Without Division)
- X -> Construct a product array such that the ith element in product array contains the product of all the remaining elements but i (Without Division) - less time complexity
- Y -> Sort a nearly sorted array, each element can be misplaced by a max of k digits before or after
- Z -> Find Duplicates in O(n) time and O(1) space - Array element values are ≤ Max Index
- ZA -> Find 2 repeating elements in a given array - XOR - Given (n+2) elements - 1 ≤ a[i] ≤ n - All elements from 1 to n occurs at least once (Except the 2 numbers that occurs twice)
- ZB -> Rotate an array of size n by d elements - Left rotation - Beginning to End - Juggling Algorithm
- ZC -> Sort array in wave form - Even position number
- ZD -> Next least greater number to the given number, input as digit array - with same digits
- ZE -> Trapping Rain Water Problem
- ZF -> No.of Triangles that can be formed
- ZG -> Smallest number that can't be formed by sum of given numbers
- ZH -> Rearrange such that a[i] becomes a[a[i]]
- ZI -> Rotate Matrix by 90 degree - anti-clockwise
- ZJ -> Count number of occurrences (or frequency) in a sorted array
- ZK -> Find Sub Array whose sum is equals zero - reduced time complexity
- ZL -> Largest sub array with equal no.of zeros and ones - my way
- ZM -> Find Duplicates in O(n) time and O(1) space - Array element values are ≤ Max Index - GFG
- ZN -> Rotate an array of size n by d elements - Left rotation - Beginning to End
- A -> Size of a Binary Tree
- B -> Identical or not
- C -> Mirror Tree
- D -> Level Order Traversal
- E -> Lowest Common Ancestor (LCA) - BST
- F -> Lowest Common Ancestor (LCA) - Binary Tree
- G -> Binary Tree into DLL - IN order - InPlace conversion
- H -> Diameter of the Binary Tree
- I -> Find the level of a given node
- J -> Print nodes at k distance form root
- K -> Print nodes at K distance from any node in BT
- L -> Vertical Tree Order Traversal
- M -> Vertical Sum of the Binary Tree
- N -> Sum Tree or not
- O -> Top View
- P -> Bottom View
- Q -> Left View
- R -> Remove all nodes whose length = K in BT.
- S -> One BT is a sub tree of another BT or not
- T -> Cousin Nodes or not
- U -> Balanced BST construction from a sorted List
- V -> Unbalanced BST into Balanced BST
- W -> Print all paths possible from root to all leaves
- X -> Spiral Level Order Traversal
- Y -> BT construction from the given POST and IN Order
- Z -> All nodes at K distance from leaf
- ZA -> Expression Evaluation
- ZB -> Extreme nodes of each level in alternating order
- ZC -> Diagonal Traversal BT
- ZD -> BT to a BT that holds Child sum property
- ZE -> Multiplication of Sums of data of leaves at same level
- ZF -> Multiplication of Sums of data at same level
- ZG -> Max of all differences of a node and it's ancestors BT
- ZH -> Serialization and Deserialization BT
- ZI -> Serialization and Deserialization n-ary Tree
- ZJ -> Tree from ancestor Matrix
- ZK -> Complete Binary Tree from a LL
- ZL -> Find the next right node of a given node in the same level
- ZM -> Boundary Traversal
- ZN -> Convert a given tree into sum tree
- ZO -> Check if Foldable or not
- ZP -> Check if removing an edge will cut into two equal halves
- ZQ -> Locking and Unlocking a Node - Design Problem
- ZR -> Reverse Alternate Levels of a perfect BT
- ZS -> Custom Tree Print Problem
- ZT -> Threaded BT
- ZU -> Remove all paths whose length < K in BT. -> Subsection of 18th Problem
- ZV -> BT construction from the given PRE and IN Order -> Subsection of 25th Problem
- A -> Reverse a LL
- B -> Middle of a LL
- C -> Kth node from the end of the LL
- D -> Detect loop in LL
- E -> Find the start of the Loop in the LL with Loop
- F -> 2 LL merge at a point, find that point
- G -> Alternating Split
- H -> Clone a LL that contains Random Pointer (Custom LL)
- I -> Palindrome of a LL
- J -> Merge 2 Sorted LL into one Sorted LL
- K -> Merge K sorted LL of size N into single Sorted LL of size kn
- L -> Merge sort on LL
- M -> LL with arb-pointer pointing to greatest in the right side of the current node
- N -> Memory efficient DLL
- O -> Sort a LL with 0s, 1s and 2s
- P -> Add 1 to number represented as LL
- Q -> Merge K sorted LL of size N into single Sorted LL of size kn - Better complexity
- A -> Stack using Queues
- B -> getMin @ O(1)
- C -> Reverse a Stack
- D -> closest greater element to the right
- E -> Overlapping Intervals
- F -> Balancing Parenthesis
- G -> Stock Span Problem
- H -> Min no.of bracket reversals req to make the eqn balanced
- I -> find duplicate parenthesis present or not
- J -> Celebrity Problem
- A -> Circular tour that visit all gasoline stations before running out of gas
- A -> Maximum Sum Sub array
- B -> Maximum Sum Increasing Sub Sequence [OR] Longest increasing Sub Sequence
- C -> Longest Sub Sequence in an array such that the element are consecutive
- D -> In a Binary Matrix, Max Square Matrix with all 1s
- E -> Kth Ugly Number
- F -> Longest Increasing Sub Sequence
- G -> Longest Decreasing Sub Sequence
- H -> Perfect Hill Sequence
- I -> Edit Distance
- J -> Largest Sum Independent set in a Binary Tree
- K -> Find n-bit integer that doesn't have 2 consecutive zeros
- L -> Word breaking problem
- M -> Partition Problem - Sub Set Sum Problem
- N -> Longest Palindromic sub sequence
- O -> Steps 1 or 2 to reach n
- P -> Longest non overlapping repeating sub string
- Q -> Min cost to make strings(x and y) equal, del(x) -> S, del(y) -> P
- R -> No.of times a string appeared as Sub Sequence in other string
- S -> No.of ways to fill 2xn with 2x1
- T -> Given a Cost matrix, min cost to reach (m-1,n-1) from (0,0), allowed movements -> left, right, diagonally down
- U -> K palindrome - If string becomes palindrome or not by doing atmost k deletions
- V -> Longest Common Sub Sequence
- W -> Sum of all digits from 1 to n
- X -> Given a string of digits, sub string length = 2k, sum of left k = sum of right k
- Y -> Given a BT, find Largest Independent Set
- Z -> Cutting Rod
- ZA -> Longest Palindromic sub string
- ZB -> Count all Palindromic sub string in a string
- ZC -> Count all distinct Palindromic sub string in a string
- ZD -> Rectangular grid 2xn, max sum such that no 2 chosen digit are adj -> vertically, horizontally, diagonally
- ZE -> Arrays A -> m, B -> n, (m>n) insert(m-n) 0s in B such that dot product is max
- ZF -> Largest Independent Set
- ZG -> Egg Dropping Problem
- ZH -> No.of Non-decreasing numbers with n digits
- ZI -> Weighted Job Scheduling
- ZJ -> Count no.of ways to reach a score in a given game, player can score 2, 4 or 6 points
- ZK -> Max coins by busting balloons
- ZL -> Max points in the grid using 2 traversals
- ZM -> Sub Set Sum Problem
- ZN -> Matrix Chaining - Results Upper triangular Matrix
- ZO -> Longest Common Sub Sequence
- ZP -> Multi Stage Graph
- ZQ -> 0/1 Knapsack
- ZR -> Travelling Sales man (TSP) - DFS based - Hamiltonian Cycle + MIN Cost
- ZS -> All Pair Shortest path - Floyd Warshall's
- ZT -> Matrix Chaining - Top Down
- ZU -> Coin Change Problem
- ZV -> Longest Palindromic sub string - Less Space Complexity
- ZW -> No.of Non-decreasing numbers with n digits - Less space
- A -> n different ropes of different length, tie them up into a single rope with Min cost.
- B -> Maximum Non Overlapping Intervals
- C -> Min no.of platforms required to station all trains without collision
- D -> Rearrange the characters in the string such that same characters become d-distance away from each other.
- E -> Dijkstra's Algorithm
- F -> Fractional Knapsack
- G -> Huffman's Coding
- H -> Job Sequencing with Deadlines
- I -> Spanning Trees and kirchhoff's theorem
- J -> Minimum Spanning Tree - Prim's
- K -> Kruskal's Algorithm
- L -> Optimal Merge Patterns
- A -> Find the element that occurs more than n/2 times - Sorted Array.
- B -> Bolt and Nuts
- C -> Implement pow()
- D -> Search an element in a sorted Rotated Array
- E -> Count Inversions in an array
- F -> Missing number in arithmetic progression
- G -> Array containing 0s before 1s, count 1s
- H -> Array has 2n elements ->
a1, a2, a3, .., an, b1, b2, .. , bn-> shuffle ->a1, b1, a2, b2, .., an, bn - I -> Sorted Array of non-repeating elements, find if there's
ifor whicha[i] = i - J ->
a[0]..a[i]-> increasing,a[i+1]..a[n]-> decreasing, find i - K -> search for an element in a row-wise and column-wise sorted 2d array.
- L -> External Sorting
- M -> Find median of 2 sorted arrays
- N -> Find Peek Element
- O -> Get first 1.
- A -> Kth bit is set or not
- B -> set Kth Bit of a number
- C -> clear Kth bit of a number
- D -> Toggle Kth bit of a number
- E -> count the no.of set bits of a number
- F -> power of 2 or not
- G -> next higher number of the given number which is a power of 2
- H -> power of 4 or not
- I -> Multiply with 7 without using
* - J -> Check if a Number is Odd or Even using Bitwise Operators
- A -> Prime or not
- B -> Print prime upto n - Sieve of Eratosthenes Algorithm
- C -> Lucky number or not
- A -> check if the array has duplicate entries at K distance or not
- B -> check if 2 sets are disjoint or not
- C -> Group all occurrences of elements order by their 1st occurrence.
- D -> Given an array A, count the distinct elements in all windows of size K
- E -> Given an array and a range (low, high). Find the elements that are in the range but not in the array.
- F -> Find the no.of sub arrays with sum zero
- G -> Find 4 elements i, j, k & l -> such that
i + j = k + l
- A -> Find a max occurring character in a given array.
- B -> Remove duplicates in a given string
- C -> Check if given 2 strings are rotations of each other
- D -> Reverse the words in the given sentence
- E -> Reverse a given string
- F -> Check if palindrome
- G -> Find 1st non-repeating character in the given string
- H -> Run length encoding
- I -> Anagrams
- J -> Excel column name for a given excel column number (MS Excel)
- K -> Find a smallest window in a string containing all characters of another string
- L -> Find 1s non-repeating character in a stream of characters
- M -> All combinations of strings used to dail a number (Old Phone Key pad)
- N -> Min no.of palindromic sub-sequences to be removed to empty a binary string
- O -> Check if given sequence of moves for robot is circular or not
- P -> Min and Max of an array using min no.of comparisons
- Q -> Convert one string to another using min no.of given operations
- R -> Print concatenation of zig-zack string in k-rows
- S -> Remove adj duplicate characters in a given string
- T -> Min no.of palindromic sub-sequences to be removed to empty a binary string - Tournament Method
- A -> Find all occurrences of str2 in str1 - Brute force
- B -> Knuth Morris Pratt Algorithm
- C -> Boyer's Moore String Matching Algorithm
- D -> Rabin-Karp String Matching Algorithm
- E -> Find all occurrences of a given word in a matrix
- A -> Finding the max element in MIN heap
- B -> Deleting arb element in MIN heap
- C -> K-Largest elements from an array
- D -> Median in a stream of numbers
- E -> Given K-sorted list, find minimum range to which at least on number belongs from every list. - All list are of same size
- F -> Convert MAX heap into MIN Heap
- G -> Print out all integers of the form
a^3+b^3where a & b are integers b/w 0 & n in sorted order. - H -> Convert BST to MAX Heap
- I -> Find the Kth largest element in a stream
- J -> Tournament Tree
- K -> Print all elements in sorted order in row wise and column wise sorted matrix
- L -> Sort a nearly sorted array
- M -> Given n ropes with different length, connect with minimum cost.
- N -> Check if the given binary tree is a max heap or not.
- O -> Given K-sorted arrays of size n-each, merge them. - different sized inner lists
- P -> Delete root from a heap.
- A -> Print all permutations of given string
- B -> Print all the strings of n-bits
- C -> N-Queens Problem
- D -> Rat in Maze
- E -> Knight Tour Problem
- F -> Find subset of elements that are selected from a given set whose sum adds upto a given number
k// Subset Sum Problem - Using Backtracking - G -> SUDOKU
- H -> N-Queens Problem - Easy way
- A -> DFS
- B -> BFS
- C -> Find if there's a path between vi and vj in a directed graph
- D -> Undirected Graph, cycle or not
- E -> Bipartite or not
- F -> Detect a cycle in a directed graph
- G -> Print all jumping numbers smaller than or equal to given value(k)
- H -> Single source shortest path - DAG
- I -> Longest Path in DAG, no weights
- J -> Find Articulation Point / Cut Vertex, Undirected
- K -> Longest Path in DAG, with weights
- L -> Topological sort