# Kth smallest or largest element in unsorted Array | Set 4

Given an array arr[] and a number K, where K is smaller than the size of the array, we need to find the Kth smallest element in the given array. It is given that all array elements are distinct.

Examples:

Input: arr[] = {7, 10, 4, 3, 20, 15}, K = 3
Output: 7

Input: arr[] = {7, 1, 5, 4, 20, 15, 8}, K = 5
Output: 8

Approach: The idea is to use the concept of Counting Sort. Below are the steps:

1. Find the maximum element(say maxE) in the array and create an array(say freq[]) of length maxE + 1 and initialize it to zero.
2. Loop through all the element in the given array and store the frequency of the element in freq[].
3. Iterate over the array freq[] until we reach the Kth element.
4. Print the Kth element reached in the above step.

Below is the implementation of above approach:

 `// C++ program for the above approach ` `#include ` `using` `namespace` `std; ` ` `  `// Function to find the Kth smallest ` `// element in Unsorted Array ` `int` `findKthSmallest(``int` `arr[], ``int` `n, ` `                    ``int` `k) ` `{ ` ` `  `    ``// Initialize the max Element as 0 ` `    ``int` `max = 0; ` ` `  `    ``// Iterate arr[] and find the maximum ` `    ``// element in it ` `    ``for` `(``int` `i = 0; i < n; i++) { ` ` `  `        ``if` `(arr[i] > max) ` `            ``max = arr[i]; ` `    ``} ` ` `  `    ``// Frequenncy array to store ` `    ``// the frequencies ` `    ``int` `counter[max + 1] = { 0 }; ` ` `  `    ``// Counter variable ` `    ``int` `smallest = 0; ` ` `  `    ``// Counting the frequencies ` `    ``for` `(``int` `i = 0; i < n; i++) { ` `        ``counter[arr[i]]++; ` `    ``} ` ` `  `    ``// Iterate through the freq[] ` `    ``for` `(``int` `num = 1; num <= max; num++) { ` ` `  `        ``// Check if num is present ` `        ``// in the array ` `        ``if` `(counter[num] > 0) { ` ` `  `            ``// Increment the counter ` `            ``// with the frequency ` `            ``// of num ` `            ``smallest += counter[num]; ` `        ``} ` ` `  `        ``// Checking if we have reached ` `        ``// the Kth smallest element ` `        ``if` `(smallest >= k) { ` ` `  `            ``// Return the Kth ` `            ``// smallest element ` `            ``return` `num; ` `        ``} ` `    ``} ` `} ` ` `  `// Driver Code ` `int` `main() ` `{ ` `    ``// Given array ` `    ``int` `arr[] = { 7, 1, 4, 4, 20, 15, 8 }; ` ` `  `    ``int` `N = ``sizeof``(arr) / ``sizeof``(arr[0]); ` ` `  `    ``int` `K = 5; ` ` `  `    ``// Function Call ` `    ``cout << findKthSmallest(arr, N, K); ` ` `  `    ``return` `0; ` `} `

Output:
```8
```

Time complexity: O(N) where, N is the number of element in the given array.
Auxiliary Space: O(M) where, M is the maximum element in the given array.

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