package algo.sortingandsearching;
/**
* Created by sherxon on 2/20/17.
*/
public class QuickSort {
public static void sort(int[] a) {
sort(a, 0, a.length - 1);
}
public static void sort(int[] a, int lo, int hi) {
if (lo >= hi) return;
int pivot = partition(a, lo, hi);
sort(a, lo, pivot - 1);
sort(a, pivot + 1, hi);
}
private static int partition(int[] a, int lo, int hi) {
int pivot = lo + (hi - lo) / 2;
swap(a, pivot, hi);
int storeIndex = lo;
for (int i = lo; i < hi; i++) {
if (a[i] < a[hi]) {
swap(a, storeIndex, i);
storeIndex++;
}
}
swap(a, hi, storeIndex);
return storeIndex;
}
private static void swap(int[] a, int i, int j) {
int temp = a[i];
a[i] = a[j];
a[j] = temp;
}
}