### Counting sort Algorithm

Want to sort numbers in a given range? Use Counting sort algorithm.
Counting sort is a integer sorting algorithm, It is a non-comparison sorting algorithm as it does not compare different elements rather it uses index of elements and their count while sorting them. Counting sort is a linear sorting algorithm and must be used when elements are in a given range and variation in the elements is not much.
It simply operates by counting the number of occurrences of  different elements in a given range, as it is a linear sorting technique it has time complexity of   O(n + k) where 'n' is the number of elements in the array and 'k' is the number of elements between max and min elements.

let us consider the below example,
let the array of numbers to be sorted be
arr = {1,3,2,1,3,3,2}
here, n = 7, min = 1, max = 3 hence k = 3

now we create a array that holds counts of all the elements, 1 has occurred 2 times, 2 has occurred 2 times and 3 has occurred 3 times thus we have
count_Array = {2, 2, 3}

Now, we construct sorted array using the count_Array, as we know 1 has occurred 2 times in the sorted array we put it 2 times and so on finally we have sorted array as

sorted_Array = {1, 1, 2, 2, 3, 3, 3}

The following image might help in understanding the idea.

Algorithm

1. Find the minimum and maximum element from the given array.
2. Initialize a count array with length as maximum - maximum and initialize all elements to 0.
3. Traverse thorough the original array and keep updating the count of each element.
4. Use the count array to place the sorted elements in the original array, using the count of each element.
Drawbacks
Though the algorithm has very less time complexity it cannot be used in general sorting cases, it can be only used when elements to be sorted are to be known in particular range.

### Sample input and output to check the program

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### Infix to Prefix conversion using Stack

This post is about conversion of Infix expression to Prefix conversion. For this conversion we take help of stack data structure, we need to push and pop the operators in and out of the stack.

Infix expressions are the expressions that we normally use,eg. 5+6-7; a+b*c etc. Prefix expressions are the expressions in which the 2 operands are preceded by the operator eg. -+567 , +a*bc etc.

This method is very similar to the method that we used to convert Infix to Postfix but the only difference is that here we need to reverse the input string before conversion and then reverse the final output string before displaying it.

NOTE: This changes one thing that is instead of encountering the opening bracket we now first encounter the closing bracket and we make changes accordingly in our code.

So, to convert an infix expression to a prefix expression we follow the below steps
(we have 2 string, 1st is the input infix expression string 2nd is the output string which is empty initially)

We first revers…

Hashing is a technique used for storing , searching and removing elements in almost constant time. Hashing is done with help of a hash function that generates index for a given input, then this index can be used to search the elements, store an element, or remove that element from that index.

A hash function is a function that is used to map the data elements to their position in the data structure used. For example if we use an array to store the integer elements then the hash function will generate position for each element so that searching, storing and removing operation on the array can be done in constant time that is independent of the number of elements in the array. For better look at the example below.

now we face a problem if for 2 numbers same position is generated example consider elements 1 and 14

1 % 13 = 1

14 % 13 = 1

so when we get 1 we store it at the first position, but when we get 14 we see that the position 1 is already taken, this is a case of collision.

Inorder…