QuickSelect.py

def quickselect(array,startind,endind,position): 
 while True:
 pivotind = startind
 leftmark = startind + 1
 rightmark = endind
 while leftmark <= rightmark:
 if array[leftmark] > array[pivotind] and array[rightmark] < array[pivotind]:
 swap(leftmark,rightmark,array)
 if array[leftmark] <= array[pivotind]:
 leftmark += 1
 if array[rightmark] >= array[pivotind]:
 rightmark -=1
 swap(pivotind, rightmark,array)
 if rightmark == position:
 print(array[rightmark])
 return
 elif rightmark < position :
 startind = rightmark+1
 else :
 endind = rightmark - 1
 
def swap(one,two,array):
 array[one],array[two]=array[two],array[one]
 
for _ in range(int(input())):
 n = int(input())
 arr = list(map(int,input().split()))
 k = int(input())
 quickselect(arr,0,n-1,k-1)