/**

* This solution is using QuickSelect method which means

* run QuickSort till the point where pivot

* is same as kth smallest element

*/

public class Solution {

public int getKthSmallest(List<Integer> a, int k) {

int size = a.size();

return kth(a,0,size-1,k);

}

public int kth(List<Integer> a, int left, int right, int k){

int pos;

if(k > 0 && k <= right - left + 1){ //if k lies within the range

pos = partition(a,left,right);

if(k == pos - left + 1){

return a.get(pos);

}

else if(k < pos - left + 1){

return kth(a,left,pos-1,k);

}

else {

return kth(a,pos+1,right,k-pos+left-1);

}

}

return Integer.MAX_VALUE;

}

public int partition(List<Integer> a, int left, int right){

int i,j,pivot,temp;

pivot = a.get(right); // I am using last element as pivot, can be changed to random or first

i = left;

for(j = left; j < right; j++){

if(a.get(j) <= pivot){

temp = a.get(i);

a.set(i,a.get(j));

a.set(j,temp);

i++;

}

}

temp = a.get(i);

a.set(i,a.get(j));

a.set(j,temp);

return i;

}

}