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# Topic:- Array

- Reverse the array
- Find the maximum and minimum element in an array
- Find the "Kth" max and min element of an array
- Given an array which consists of only 0, 1 and 2. Sort the array without using any sorting algo
- Move all the negative elements to one side of the array
- Find the Union and Intersection of the two sorted arrays.
- Write a program to cyclically rotate an array by one.
- find Largest sum contiguous Subarray [V. IMP]
- Minimise the maximum difference between heights [V.IMP]
- Minimum no. of Jumps to reach end of an array
- find duplicate in an array of N+1 Integers
- Merge 2 sorted arrays without using Extra space.
- Kadane's Algo [V.V.V.V.V IMP]
- Merge Intervals
- Next Permutation
- Count Inversion
- Best time to buy and Sell stock
- find all pairs on integer array whose sum is equal to given number
- find common elements In 3 sorted arrays
- Rearrange the array in alternating positive and negative items with O(1) extra space
- Find if there is any subarray with sum equal to 0
- Find factorial of a large number
- find maximum product subarray
- Find longest coinsecutive subsequence
- Given an array of size n and a number k, fin all elements that appear more than " n/k " times.
- Maximum profit by buying and selling a share atmost twice
- Find whether an array is a subset of another array
- Find the triplet that sum to a given value
- Trapping Rain water problem
- Chocolate Distribution problem
- Smallest Subarray with sum greater than a given value
- Three way partitioning of an array around a given value
- Minimum swaps required bring elements less equal K together
- Minimum no. of operations required to make an array palindrome
- Median of 2 sorted arrays of equal size
- Median of 2 sorted arrays of different size
- Spiral traversal on a Matrix
- Search an element in a matriix
- Find median in a row wise sorted matrix
- Find row with maximum no. of 1's
- Print elements in sorted order using row-column wise sorted matrix
- Maximum size rectangle
- Find a specific pair in matrix
- Rotate matrix by 90 degrees
- Kth smallest element in a row-cpumn wise sorted matrix
- Common elements in all rows of a given matrix
- Reverse a String
- Check whether a String is Palindrome or not
- Find Duplicate characters in a string
- Why strings are immutable in Java?
- Write a Code to check whether one string is a rotation of another
- Write a Program to check whether a string is a valid shuffle of two strings or not
- Count and Say problem
- Write a program to find the longest Palindrome in a string.[ Longest palindromic Substring]
- Find Longest Recurring Subsequence in String
- Print all Subsequences of a string.
- Print all the permutations of the given string
- Split the Binary string into two substring with equal 0’s and 1’s
- Word Wrap Problem [VERY IMP].
- EDIT Distance [Very Imp]
- Find next greater number with same set of digits. [Very Very IMP]
- Balanced Parenthesis problem.[Imp]
- Word break Problem[ Very Imp]
- Rabin Karp Algo
- KMP Algo
- Convert a Sentence into its equivalent mobile numeric keypad sequence.
- Minimum number of bracket reversals needed to make an expression balanced.
- Count All Palindromic Subsequence in a given String.
- Count of number of given string in 2D character array
- Search a Word in a 2D Grid of characters.
- Boyer Moore Algorithm for Pattern Searching.
- Converting Roman Numerals to Decimal
- Longest Common Prefix
- Number of flips to make binary string alternate
- Find the first repeated word in string.
- Minimum number of swaps for bracket balancing.
- Find the longest common subsequence between two strings.
- Program to generate all possible valid IP addresses from given string.
- Write a program tofind the smallest window that contains all characters of string itself.
- Rearrange characters in a string such that no two adjacent are same
- Minimum characters to be added at front to make string palindrome
- Given a sequence of words, print all anagrams together
- Find the smallest window in a string containing all characters of another string
- Recursively remove all adjacent duplicates
- String matching where one string contains wildcard characters
- Function to find Number of customers who could not get a computer
- Transform One String to Another using Minimum Number of Given Operation
- Check if two given strings are isomorphic to each other
- Recursively print all sentences that can be formed from list of word lists
- Find first and last positions of an element in a sorted array
- Find a Fixed Point (Value equal to index) in a given array
- Search in a rotated sorted array
- square root of an integer
- Maximum and minimum of an array using minimum number of comparisons
- Optimum location of point to minimize total distance
- Find the repeating and the missing
- find majority element
- Searching in an array where adjacent differ by at most k
- find a pair with a given difference
- find four elements that sum to a given value
- maximum sum such that no 2 elements are adjacent
- Count triplet with sum smaller than a given value
- merge 2 sorted arrays
- print all subarrays with 0 sum
- Product array Puzzle
- Sort array according to count of set bits
- minimum no. of swaps required to sort the array
- Bishu and Soldiers
- Rasta and Kheshtak
- Kth smallest number again
- Find pivot element in a sorted array
- K-th Element of Two Sorted Arrays
- Aggressive cows
- Book Allocation Problem
- EKOSPOJ:
- Job Scheduling Algo
- Missing Number in AP
- Smallest number with atleastn trailing zeroes infactorial
- Painters Partition Problem:
- ROTI-Prata SPOJ
- DoubleHelix SPOJ
- Subset Sums
- Findthe inversion count
- Implement Merge-sort in-place
- Partitioning and Sorting Arrays with Many Repeated Entries
- Write a Program to reverse the Linked List. (Both Iterative and recursive)
- Reverse a Linked List in group of Given Size. [Very Imp]
- Write a program to Detect loop in a linked list.
- Write a program to Delete loop in a linked list.
- Find the starting point of the loop.
- Remove Duplicates in a sorted Linked List.
- Remove Duplicates in a Un-sorted Linked List.
- Write a Program to Move the last element to Front in a Linked List.
- Add “1” to a number represented as a Linked List.
- Add two numbers represented by linked lists.
- Intersection of two Sorted Linked List.
- Intersection Point of two Linked Lists.
- Merge Sort For Linked lists.[Very Important]
- Quicksort for Linked Lists.[Very Important]
- Find the middle Element of a linked list.
- Check if a linked list is a circular linked list.
- Split a Circular linked list into two halves.
- Write a Program to check whether the Singly Linked list is a palindrome or not.
- Deletion from a Circular Linked List.
- Reverse a Doubly Linked list.
- Find pairs with a given sum in a DLL.
- Count triplets in a sorted DLL whose sum is equal to given value “X”.
- Sort a “k”sorted Doubly Linked list.[Very IMP]
- Rotate DoublyLinked list by N nodes.
- Rotate a Doubly Linked list in group of Given Size.[Very IMP]
- Can we reverse a linked list in less than O(n) ?
- Why Quicksort is preferred for. Arrays and Merge Sort for LinkedLists ?
- Flatten a Linked List
- Sort a LL of 0's, 1's and 2's
- Clone a linked list with next and random pointer
- Merge K sorted Linked list
- Multiply 2 no. represented by LL
- Delete nodes which have a greater value on right side
- Segregate even and odd nodes in a Linked List
- Program for n’th node from the end of a Linked List
- Find the first non-repeating character from a stream of characters
- level order traversal
- Reverse Level Order traversal
- Height of a tree
- Diameter of a tree
- Mirror of a tree
- Inorder Traversal of a tree both using recursion and Iteration
- Preorder Traversal of a tree both using recursion and Iteration
- Postorder Traversal of a tree both using recursion and Iteration
- Left View of a tree
- Right View of Tree
- Top View of a tree
- Bottom View of a tree
- Zig-Zag traversal of a binary tree
- Check if a tree is balanced or not
- Diagnol Traversal of a Binary tree
- Boundary traversal of a Binary tree
- Construct Binary Tree from String with Bracket Representation
- Convert Binary tree into Doubly Linked List
- Convert Binary tree into Sum tree
- Construct Binary tree from Inorder and preorder traversal
- Find minimum swaps required to convert a Binary tree into BST
- Check if Binary tree is Sum tree or not
- Check if all leaf nodes are at same level or not
- Check if a Binary Tree contains duplicate subtrees of size 2 or more [ IMP ]
- Check if 2 trees are mirror or not
- Sum of Nodes on the Longest path from root to leaf node
- Check if given graph is tree or not. [ IMP ]
- Find Largest subtree sum in a tree
- Maximum Sum of nodes in Binary tree such that no two are adjacent
- Print all "K" Sum paths in a Binary tree
- Find LCA in a Binary tree
- Find distance between 2 nodes in a Binary tree
- Kth Ancestor of node in a Binary tree
- Find all Duplicate subtrees in a Binary tree [ IMP ]
- Tree Isomorphism Problem
- Fina a value in a BST
- Deletion of a node in a BST
- Find min and max value in a BST
- Find inorder successor and inorder predecessor in a BST
- Check if a tree is a BST or not
- Populate Inorder successor of all nodes
- Find LCA of 2 nodes in a BST
- Construct BST from preorder traversal
- Convert Binary tree into BST
- Convert a normal BST into a Balanced BST
- Merge two BST [ V.V.V>IMP ]
- Find Kth largest element in a BST
- Find Kth smallest element in a BST
- Count pairs from 2 BST whose sum is equal to given value "X"
- Find the median of BST in O(n) time and O(1) space
- Count BST ndoes that lie in a given range
- Replace every element with the least greater element on its right
- Given "n" appointments, find the conflicting appointments
- Check preorder is valid or not
- Check whether BST contains Dead end
- Largest BST in a Binary Tree [ V.V.V.V.V IMP ]
- Flatten BST to sorted list
- Activity Selection Problem
- Job SequencingProblem
- Huffman Coding
- Water Connection Problem
- Fractional Knapsack Problem
- Greedy Algorithm to find Minimum number of Coins
- Maximum trains for which stoppage can be provided
- Minimum Platforms Problem
- Buy Maximum Stocks if i stocks can be bought on i-th day
- Find the minimum and maximum amount to buy all N candies
- Minimize Cash Flow among a given set of friends who have borrowed money from each other
- Minimum Cost to cut a board into squares
- Check if it is possible to survive on Island
- Find maximum meetings in one room
- Maximum product subset of an array
- Maximize array sum after K negations
- Maximize the sum of arr[i]*i
- Maximum sum of absolute difference of an array
- Maximize sum of consecutive differences in a circular array
- Minimum sum of absolute difference of pairs of two arrays
- Program for Shortest Job First (or SJF) CPU Scheduling
- Program for Least Recently Used (LRU) Page Replacement algorithm
- Smallest subset with sum greater than all other elements
- Chocolate Distribution Problem
- DEFKIN -Defense of a Kingdom
- DIEHARD -DIE HARD
- GERGOVIA -Wine trading in Gergovia
- Picking Up Chicks
- CHOCOLA –Chocolate
- ARRANGE -Arranging Amplifiers
- K Centers Problem
- Minimum Cost of ropes
- Find smallest number with given number of digits and sum of digits
- Rearrange characters in a string such that no two adjacent are same
- Find maximum sum possible equal sum of three stacks
- Rat in a maze Problem
- Printing all solutions in N-Queen Problem
- Word Break Problem using Backtracking
- Remove Invalid Parentheses
- Sudoku Solver
- m Coloring Problem
- Print all palindromic partitions of a string
- Subset Sum Problem
- The Knight’s tour problem
- Tug of War
- Find shortest safe route in a path with landmines
- Combinational Sum
- Find Maximum number possible by doing at-most K swaps
- Print all permutations of a string
- Find if there is a path of more than k length from a source
- Longest Possible Route in a Matrix with Hurdles
- Print all possible paths from top left to bottom right of a mXn matrix
- Partition of a set intoK subsets with equal sum
- Find the K-th Permutation Sequence of first N natural numbers
- Implement Stack from Scratch
- Implement Queue from Scratch
- Implement 2 stack in an array
- find the middle element of a stack
- Implement "N" stacks in an Array
- Check the expression has valid or Balanced parenthesis or not.
- Reverse a String using Stack
- Design a Stack that supports getMin() in O(1) time and O(1) extra space.
- Find the next Greater element
- The celebrity Problem
- Arithmetic Expression evaluation
- Evaluation of Postfix expression
- Implement a method to insert an element at its bottom without using any other data structure.
- Reverse a stack using recursion
- Sort a Stack using recursion
- Merge Overlapping Intervals
- Largest rectangular Area in Histogram
- Length of the Longest Valid Substring
- Expression contains redundant bracket or not
- Implement Stack using Queue
- Implement Stack using Deque
- Stack Permutations (Check if an array is stack permutation of other)
- Implement Queue using Stack
- Implement "n" queue in an array
- Implement a Circular queue
- LRU Cache Implementationa
- Reverse a Queue using recursion
- Reverse the first “K” elements of a queue
- Interleave the first half of the queue with second half
- Find the first circular tour that visits all Petrol Pumps
- Minimum time required to rot all oranges
- Distance of nearest cell having 1 in a binary matrix
- First negative integer in every window of size “k”
- Check if all levels of two trees are anagrams or not.
- Sum of minimum and maximum elements of all subarrays of size “k”.
- Minimum sum of squares of character counts in a given string after removing “k” characters.
- Queue based approach or first non-repeating character in a stream.
- Next Smaller Element
- Implement a Maxheap/MinHeap using arrays and recursion.
- Sort an Array using heap. (HeapSort)
- Maximum of all subarrays of size k.
- “k” largest element in an array
- Kth smallest and largest element in an unsorted array
- Merge “K” sorted arrays. [ IMP ]
- Merge 2 Binary Max Heaps
- Kth largest sum continuous subarrays
- Leetcode- reorganize strings
- Merge “K” Sorted Linked Lists [V.IMP]
- Smallest range in “K” Lists
- Median in a stream of Integers
- Check if a Binary Tree is Heap
- Connect “n” ropes with minimum cost
- Convert BST to Min Heap
- Convert min heap to max heap
- Rearrange characters in a string such that no two adjacent are same.
- Minimum sum of two numbers formed from digits of an array
- Create a Graph, print it
- Implement BFS algorithm
- Implement DFS Algo
- Detect Cycle in Directed Graph using BFS/DFS Algo
- Detect Cycle in UnDirected Graph using BFS/DFS Algo
- Search in a Maze
- Minimum Step by Knight
- flood fill algo
- Clone a graph
- Making wired Connections
- word Ladder
- Dijkstra algo
- Implement Topological Sort
- Minimum time taken by each job to be completed given by a Directed Acyclic Graph
- Find whether it is possible to finish all tasks or not from given dependencies
- Find the no. of Isalnds
- Given a sorted Dictionary of an Alien Language, find order of characters
- Implement Kruksal’sAlgorithm
- Implement Prim’s Algorithm
- Total no. of Spanning tree in a graph
- Implement Bellman Ford Algorithm
- Implement Floyd warshallAlgorithm
- Travelling Salesman Problem
- Graph ColouringProblem
- Snake and Ladders Problem
- Find bridge in a graph
- Count Strongly connected Components(Kosaraju Algo)
- Check whether a graph is Bipartite or Not
- Detect Negative cycle in a graph
- Longest path in a Directed Acyclic Graph
- Journey to the Moon
- Cheapest Flights Within K Stops
- Oliver and the Game
- Water Jug problem using BFS
- Water Jug problem using BFS
- Find if there is a path of more thank length from a source
- M-ColouringProblem
- Minimum edges to reverse o make path from source to destination
- Paths to travel each nodes using each edge(Seven Bridges)
- Vertex Cover Problem
- Chinese Postman or Route Inspection
- Number of Triangles in a Directed and Undirected Graph
- Minimise the cashflow among a given set of friends who have borrowed money from each other
- Two Clique Problem
- Construct a trie from scratch
- Find shortest unique prefix for every word in a given list
- Word Break Problem | (Trie solution)
- Given a sequence of words, print all anagrams together
- Implement a Phone Directory
- Print unique rows in a given boolean matrix
- Coin ChangeProblem
- Knapsack Problem
- Binomial CoefficientProblem
- Permutation CoefficientProblem
- Program for nth Catalan Number
- Matrix Chain Multiplication
- Edit Distance
- Subset Sum Problem
- Friends Pairing Problem
- Gold Mine Problem
- Assembly Line SchedulingProblem
- Painting the Fenceproblem
- Maximize The Cut Segments
- Longest Common Subsequence
- Longest Repeated Subsequence
- Longest Increasing Subsequence
- Space Optimized Solution of LCS
- LCS (Longest Common Subsequence) of three strings
- Maximum Sum Increasing Subsequence
- Count all subsequences having product less than K
- Longest subsequence such that difference between adjacent is one
- Maximum subsequence sum such that no three are consecutive
- Egg Dropping Problem
- Maximum Length Chain of Pairs
- Maximum size square sub-matrix with all 1s
- Maximum sum of pairs with specific difference
- Min Cost PathProblem
- Maximum difference of zeros and ones in binary string
- Minimum number of jumps to reach end
- Minimum cost to fill given weight in a bag
- Minimum removals from array to make max –min <= K
- Longest Common Substring
- Count number of ways to reacha given score in a game
- Count Balanced Binary Trees of Height h
- LargestSum Contiguous Subarray [V>V>V>V IMP ]
- Smallest sum contiguous subarray
- Unbounded Knapsack (Repetition of items allowed)
- Word Break Problem
- Largest Independent Set Problem
- Partition problem
- Longest Palindromic Subsequence
- Count All Palindromic Subsequence in a given String
- Longest Palindromic Substring
- Longest alternating subsequence
- Weighted Job Scheduling
- Coin game winner where every player has three choices
- Count Derangements (Permutation such that no element appears in its original position) [ IMPORTANT ]
- Maximum profit by buying and selling a share at most twice [ IMP ]
- Optimal Strategy for a Game
- Optimal Binary Search Tree
- Palindrome PartitioningProblem
- Word Wrap Problem
- Mobile Numeric Keypad Problem [ IMP ]
- Boolean Parenthesization Problem
- Largest rectangular sub-matrix whose sum is 0
- Largest area rectangular sub-matrix with equal number of 1’s and 0’s [ IMP ]
- Maximum sum rectangle in a 2D matrix
- Maximum profit by buying and selling a share at most k times
- Find if a string is interleaved of two other strings
- Maximum Length of Pair Chain
- Count set bits in an integer
- Find the two non-repeating elements in an array of repeating elements
- Count number of bits to be flipped to convert A to B
- Count total set bits in all numbers from 1 to n
- Program to find whether a no is power of two
- Find position of the only set bit
- Copy set bits in a range
- Divide two integers without using multiplication, division and mod operator
- Calculate square of a number without using *, / and pow()
- Power Set

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