# Array Data Structure

### Recent articles on Arrays

**Topics :**

- Program for array rotation
- Reversal algorithm for array rotation
- Block swap algorithm for array rotation
- Program to cyclically rotate an array by one
- Search an element in a sorted and rotated array
- Given a sorted and rotated array, find if there is a pair with a given sum
- Find maximum value of Sum( i*arr[i]) with only rotations on given array allowed
- Maximum sum of i*arr[i] among all rotations of a given array
- Find the Rotation Count in Rotated Sorted array
- Quickly find multiple left rotations of an array
- Find the minimum element in a sorted and rotated array
- Reversal algorithm for right rotation of an array
- Find a rotation with maximum hamming distance
- Queries on Left and Right Circular shift on array
- Print left rotation of array in O(n) time and O(1) space
- Find element at given index after a number of rotations
- Split the array and add the first part to the end

- Rearrange an array such that arr[i] = i
- Write a program to reverse an array or string
- Rearrange array such that arr[i] >= arr[j] if i is even and arr[i]<=arr[j] if i is odd and j < i
- Rearrange positive and negative numbers in O(n) time and O(1) extra space
- Rearrange array in alternating positive & negative items with O(1) extra space | Set 1
- Move all zeroes to end of array
- Move all zeroes to end of array | Set-2 (Using single traversal)
- Minimum swaps required to bring all elements less than or equal to k together
- Rearrange positive and negative numbers using inbuilt sort function
- Rearrange array such that even positioned are greater than odd
- Rearrange an array in order – smallest, largest, 2nd smallest, 2nd largest, ..
- Double the first element and move zero to end
- Reorder an array according to given indexes
- Rearrange positive and negative numbers with constant extra space
- Arrange given numbers to form the biggest number
- Rearrange an array such that ‘arr[j]’ becomes ‘i’ if ‘arr[i]’ is ‘j’
- Rearrange an array in maximum minimum form | Set 1
- Rearrange an array in maximum minimum form | Set 2 (O(1) extra space)
- Move all negative numbers to beginning and positive to end with constant extra space
- Move all negative elements to end in order with extra space allowed
- Rearrange array such that even index elements are smaller and odd index elements are greater
- Positive elements at even and negative at odd positions
- Replace every array element by multiplication of previous and next
- Shuffle a given array
- Segregate even and odd numbers

- K’th Smallest/Largest Element in Unsorted Array | Set 1
- K’th Smallest/Largest Element in Unsorted Array | Set 2 (Expected Linear Time)
- K’th Smallest/Largest Element in Unsorted Array | Set 3 (Worst Case Linear Time)
- K’th Smallest/Largest Element using STL
- k largest(or smallest) elements in an array | added Min Heap method
- Kth smallest element in a row-wise and column-wise sorted 2D array | Set 1
- Program to find largest element in an array
- Find the largest three elements in an array
- Find all elements in array which have at-least two greater elements
- Program for Mean and median of an unsorted array
- Median of Stream of Running Integers using STL
- Minimum product of k integers in an array of positive Integers
- K-th Largest Sum Contiguous Subarray
- K maximum sum combinations from two arrays
- K maximum sums of overlapping contiguous sub-arrays
- K maximum sums of non-overlapping contiguous sub-arrays
- k smallest elements in same order using O(1) extra space
- Find k pairs with smallest sums in two arrays
- k-th smallest absolute difference of two elements in an array
- Find Second largest element in an array
- Find k numbers with most occurrences in the given array
- Find the smallest and second smallest elements in an array
- Find the smallest missing number
- Maximum sum such that no two elements are adjacent
- Maximum and minimum of an array using minimum number of comparisons

- MO’s Algorithm
- Sqrt (or Square Root) Decomposition Technique | Set 1 (Introduction)
- Sparse Table
- Range sum query using Sparse Table
- Range Minimum Query (Square Root Decomposition and Sparse Table)
- Range Queries for Frequencies of array elements
- Constant time range add operation on an array
- Range LCM Queries
- GCDs of given index ranges in an array
- Queries for GCD of all numbers of an array except elements in a given range
- Number of elements less than or equal to a given number in a given subarray
- Number of elements less than or equal to a given number in a given subarray | Set 2 (Including Updates)
- Queries for counts of array elements with values in given range
- Queries for decimal values of subarrays of a binary array
- Count elements which divide all numbers in range L-R
- Number whose sum of XOR with given array range is maximum
- XOR of numbers that appeared even number of times in given Range
- Array range queries over range queries
- Array range queries for searching an element
- Array range queries for elements with frequency same as value
- Maximum Occurrence in a Given Range
- Number of indexes with equal elements in given range
- Merge Sort Tree for Range Order Statistics
- Total numbers with no repeated digits in a range
- Difference Array | Range update query in O(1)

- Largest Sum Contiguous Subarray
- Maximum profit by buying and selling a share at most twice
- Find the subarray with least average
- Find the minimum distance between two numbers
- Minimize the maximum difference between the heights
- Minimum number of jumps to reach end
- Dynamic Programming | Set 14 (Maximum Sum Increasing Subsequence)
- Smallest subarray with sum greater than a given value
- Find maximum average subarray of k length
- Count minimum steps to get the given desired array
- Number of subsets with product less than k
- Find minimum number of merge operations to make an array palindrome
- Find the smallest positive integer value that cannot be represented as sum of any subset of a given array
- Size of The Subarray With Maximum Sum
- Find minimum difference between any two elements
- Space optimization using bit manipulations
- Longest Span with same Sum in two Binary arrays

- Alternative Sorting
- Sort a nearly sorted (or K sorted) array
- Sort an array according to absolute difference with given value
- Sort an array in wave form
- Merge an array of size n into another array of size m+n
- Sort an array which contain 1 to n values
- Sort 1 to N by swapping adjacent elements
- Sort an array containing two types of elements
- Sort elements by frequency | Set 1
- Count Inversions in an array | Set 1 (Using Merge Sort)
- Two elements whose sum is closest to zero
- Shortest Un-ordered Subarray
- Minimum number of swaps required to sort an array
- Union and Intersection of two sorted arrays
- Find Union and Intersection of two unsorted arrays
- Sort an array of 0s, 1s and 2s
- Find the Minimum length Unsorted Subarray, sorting which makes the complete array sorted
- Median in a stream of integers (running integers)
- Count the number of possible triangles
- Find number of pairs (x, y) in an array such that x^y > y^x
- Count all distinct pairs with difference equal to k
- Print All Distinct Elements of a given integer array
- Construct an array from its pair-sum array
- Merge two sorted arrays with O(1) extra space
- Product of maximum in first array and minimum in second

- Search, insert and delete in an unsorted array
- Search, insert and delete in a sorted array
- Given an array A[] and a number x, check for pair in A[] with sum as x
- Searching in an array where adjacent differ by at most k
- Find common elements in three sorted arrays
- Find position of an element in a sorted array of infinite numbers
- Find the only repetitive element between 1 to n-1
- Find the element that appears once
- Maximum Subarray Sum Excluding Certain Elements
- Maximum equlibrium sum in an array
- Equilibrium index of an array
- Leaders in an array
- Ceiling in a sorted array
- Majority Element
- Check for Majority Element in a sorted array
- Check if an array has a majority element
- Two Pointers Technique
- Find a peak element
- Find the two repeating elements in a given array
- Find a Fixed Point in a given array
- Find sub-array with given sum
- Maximum triplet sum in array
- Smallest Difference Triplet from Three arrays
- Find a triplet that sum to a given value
- Find all triplets with zero sum

- Rotate Matrix Elements
- Inplace rotate square matrix by 90 degrees | Set 1
- Rotate a matrix by 90 degree without using any extra space | Set 2
- Rotate a Matrix by 180 degree
- Turn an image by 90 degree
- Rotate each ring of matrix anticlockwise by K elements
- Check if all rows of a matrix are circular rotations of each other
- Sort the given matrix
- Find the row with maximum number of 1s
- Find median in row wise sorted matrix
- Matrix Multiplication | Recursive
- Program to multiply two matrices
- Program for scalar multiplication of a matrix
- Program to print Lower triangular and Upper triangular matrix of an array
- Find distinct elements common to all rows of a matrix
- Print a given matrix in spiral form
- Find maximum element of each row in a matrix
- Find unique elements in a matrix
- Shift matrix elements row-wise by k
- Different Operations on Matrices
- Print a given matrix in counter-clock wise spiral form
- Swap major and minor diagonals of a square matrix
- Maximum path sum in matrix
- Squares of Matrix Diagonal Elements
- Move matrix elements in given direction and add elements with same value

- Subarray/Substring vs Subsequence and Programs to Generate them
- A Product Array Puzzle
- Number of subarrays with given product
- Linked List vs Array
- Check if array elements are consecutive | Added Method 3
- Find whether an array is subset of another array | Added Method 3
- Implement two stacks in an array
- Find relative complement of two sorted arrays
- Minimum increment by k operations to make all elements equal
- Minimize (max(A[i], B[j], C[k]) – min(A[i], B[j], C[k])) of three different sorted arrays

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