Array Rotation - Three Solutions

Array rotation by k places can be done by using extra space of k sized array, by shifting array by one position in loop of k, by shifting array by gcd(array.length, k) in gcd number of sets. Following program has all the implementations:

Top K Frequent Elements - Hashing Problem

Problem : Get top K frequent elements.

Implementation:

Sort By Frequency - Hashing Problem

Problem : Sort elements by their frequency.

Following is the implementation where we store the frequency in hashmap:

Count Distinct Elements In Every Window - Hashing Problem

Problem: Count distinct elements in every window of given K size.

Following is the implementation, which rotates the array window:

Print Non-repeated Elements - Hashing Problems

Problem : Print the non-repeated elements of an array.

Following is the implementation:

Relative Sorting - Hashing Problems

Problem : Sort array1 in the order of array2 elements.

Following is the implementation:

Zero Sum Sub-arrays Count - Hashing Problems

Problem : Find the number of sub-arrays whose sum evaluates to zero.

Following is the implementation:

Largest Sub-array With Sum Zero - Hashing Problem

Problem : Find the maximum length of the largest sub-array with sum zero.

Following is the implementation, where we store the sum at every index in hashmap and look for sum already being present in hashmap(only possible if sum of the sub-array is zero):

Four Sum - Hashing Problems

Problem : Find four elements in array whose sum equals to x.

Following is the implementation using hashmap:

Two Sum - Hashing Problem

Problem : Find two elements in an array whose sum is x.

Following is the implementation:

Longest Consequent Sub-sequence - Hashing Problem

To find longest consequent sub-sequence in an array, following is the implementation using hashmap:

Maximum Distance Between Two Occurences Of Same Element - Hashing Problem

To find the maximum distance between two occurrences of same element, we can store the elements in hashmap and compare max index distance. Following is the implementation:

Check If Two Arrays Are Equal - Hashing Problems

To check if two arrays are equals, lengths and elements along with their frequency need to be considered. For this, a hashmap can be used. Following is the implementation: