K-th Smallest Element

Return the k-th smallest value of the list (k counts from 1). Quickselect finds it in average O(n) time without sorting everything.

Implement kth_smallest(numbers, k).

Input

numbers: The list of integers. k: Which smallest value to return, starting at 1.

Output

Return the k-th smallest value.

Contraintes

1 ≤ k ≤ length ≤ 200,000

Exemples

Entrée :
k = 3
numbers = [7, 10, 4, 3, 20, 15]

Sortie attendue :
expected = 7

Entrée :
long long k = 3;
std::vector<long long> numbers = {7, 10, 4, 3, 20, 15};

Sortie attendue :
long long expected = 7;

Entrée :
long k = 3;
long[] numbers = new long[] {7, 10, 4, 3, 20, 15};

Sortie attendue :
long expected = 7;

Entrée :
k = 2
numbers = [5, 5, 1]

Sortie attendue :
expected = 5

Entrée :
long long k = 2;
std::vector<long long> numbers = {5, 5, 1};

Sortie attendue :
long long expected = 5;

Entrée :
long k = 2;
long[] numbers = new long[] {5, 5, 1};

Sortie attendue :
long expected = 5;

Références

Ce défi a été adapté pour CodeUtility. Suivez l'énoncé et les contraintes ci-dessus.

• Wikipedia: Quickselect