In java, check if the quicksort algorithm is correctly implemented. If not, edit the code to fix it.

public class KthSmallest {

private static void swap(int[] theArray, int i, int j){

int temp = theArray[i];

theArray[i] = theArray[j];

theArray[j] = temp;

}

private static int partition(int[] theArray, int first, int last){

// Returns the index of the pivot element after partitioning

// theArray[first..last]

int p = theArray[first]; // use the first item of the array as the pivot (p)

int lastS1 = first; // set S1 and S2 to empty

// ToDo: Determine the regions S1 and S2

// Refer to the quicksort algorithm

while (first <= last) {

//searching number which is greater than pivot, bottom up

while(theArray[first]< p) {

first++;

}

//searching number which is less than pivot, top down

while (theArray[last] > p) {

last--;

}

//swap the values

if (first <= last) {

int tmp = theArray[first];

theArray[first] = theArray[last];

theArray[last] = tmp;

//increment first index and decrement last index

first++;

last--;

}

}

return lastS1; // the index of the pivot element

}