Last Updated: 21 Nov, 2020
Kth Smallest Element
Easy
Asked in companies
You are given an array of integers 'ARR' of size 'N' and another integer 'K'.
Your task is to find and return 'K'th smallest value present in the array.
Note: All the elements in the array are distinct.
Example
If 'N' is 5 and 'K' is 3 and the array is 7, 2, 6, 1, 9
Sorting the array we get 1, 2, 6, 7, 9
Hence the 3rd smallest number is 6.
Input format
The first line contains two space-separated integers ‘N’ representing the size of the array and ‘K’.
The second line contains 'N' space-separated integers that represent elements of the array 'ARR'.
Output format
Print a single line that contains a single integer which is the 'Kth' smallest element of the array.
Note:
You do not need to print anything; it has already been taken care of. Just implement the given function.
Approaches
- Sort the elements of ‘ARR’ using function ‘SORT’
- Return element at ('K' - 1)th index
- We’ll use min heaps to store the elements of 'ARR' and perform 'K' GETMIN operations to get Kth minimum element.
- We’ll create an empty heap MINHEAP.
- We’ll add 'ARR'['I'] to MINHEAP for each 0 <= 'I' < 'N'. Every time the element is added the structure will HEAPIFY itself, such that the minimum element is always at the root node of the heap.
- Call GETMIN function 'K' times and store the result in 'KTHMIN' variable.
- Return 'KTHMIN'.
We’ll use a max heap of fixed size 'K' to store the elements of 'ARR' and perform a single 'GETMAX' operation to get 'K'th minimum element.
- We’ll create an empty heap 'MAXHEAP'.
- We’ll add 'ARR'['I'] to 'MAXHEAP' for each 0 <= 'I' < 'K'. Every time the element is added the structure will HEAPIFY itself, such that the maximum element is always at the root node of the heap.
- For each 'I' where, 'K' <= 'I' <= N, If 'ARR'['I'] < 'MAXHEAP'.'GETMAX'
- Replace ROOT of 'MAXHEAP' by 'ARR'['I'] .
- HEAPIFY the 'MAXHEAP'.
- Call 'GETMAX' and store its value in 'KTHMIN'.
- Return 'KTHMIN'.