/* package whatever; // don't place package name! */ import java.util.*; import java.lang.*; import java.io.*; /* Name of the class has to be "Main" only if the class is public. */ class Ideone { public static void swap(int[] arr, int i, int j){ int temp =arr[i]; arr[i] = arr[j]; arr[j] = temp; } public static int partition(int[] arr, int start, int end) { int pivot = end; int index = start; for(int j = start; j < end; j++){ if(arr[j] <= arr[pivot]) { swap(arr, index, j); index++; } } swap(arr, index, pivot); return index; } public static void quickSort(int[] arr, int start, int end) { if(start < end) { int pivot = partition(arr, start, end); quickSort(arr, start, pivot-1); quickSort(arr, pivot+1, end); } } public static void main (String[] args) throws java.lang.Exception { int[] arr = {10, 80, 30, 90, 40, 50 ,70}; quickSort(arr, 0, arr.length-1); System.out.println(Arrays.toString(arr)); } }