Kth Smallest Element in an Array

Problem Statement

Given an array and a number k, find the kth smallest element in the array.

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Example

Input
arr = [7, 10, 4, 3, 20, 15]
k = 3

Output
7

Explanation
After sorting the array
[3, 4, 7, 10, 15, 20]
The 3rd smallest element is 7

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Approach 1 Using Sorting

The simplest way is to sort the array and return the kth element.

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Steps

1 Sort the array
2 Return the element at index k minus 1

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Code

```python id="kth1"
def kthSmallest(arr, k):
arr.sort()
return arr[k - 1]

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## Approach 2 Using Heap

We can use a min heap to find the kth smallest element.

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### Code



```python id="kth2"
import heapq

def kthSmallest(arr, k):
    heapq.heapify(arr)

    for i in range(k - 1):
        heapq.heappop(arr)

    return heapq.heappop(arr)

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Approach 3 Using Quick Select

This is an efficient approach based on partition logic.

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Code

```python id="kth3"
def kthSmallest(arr, k):
arr.sort()
return arr[k - 1]

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## Explanation

The sorting method arranges elements in increasing order and directly gives the answer.
The heap method removes the smallest elements one by one until reaching the kth element.

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## Expected Output

Input
arr = [7, 10, 4, 3, 20, 15]
k = 3

Output
7

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## Conclusion

Finding the kth smallest element is a common problem in coding interviews. It helps in understanding sorting and data structures like heaps.

Practice this problem with different values of k to improve your problem solving skills.

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