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import java.util.Arrays; import java.util.Random;
public class QuickSort {
private QuickSort(){}
public static <E extends Comparable<E>> void sort(E[] arr){ Random rnd = new Random(); sort(arr, 0, arr.length-1, rnd); }
private static <E extends Comparable<E>> void sort(E[] arr, int l , int r, Random rnd){
if(l >= r) return;
int p = partition(arr, l , r, rnd); sort(arr, l, p-1, rnd); sort(arr, p+1 , r, rnd); }
private static <E extends Comparable<E>> int partition(E[] arr, int l, int r, Random rnd){
int p = l + rnd.nextInt(r-l+1); swap(arr, l , p); int j=l; for(int i = l + 1; i<= r; i++){ if(arr[i].compareTo(arr[l]) < 0){ j ++; swap(arr, j, i); } } swap(arr, l,j); return j;
}
public static <E extends Comparable<E>> void sort2ways(E[] arr){ Random rnd = new Random(); sort2ways(arr, 0, arr.length-1, rnd); }
private static <E extends Comparable<E>> void sort2ways(E[] arr, int l , int r, Random rnd){
if(l >= r) return;
int p = partition2(arr, l , r, rnd); sort2ways(arr, l, p-1, rnd); sort2ways(arr, p+1 , r, rnd); }
private static <E extends Comparable<E>> int partition2(E[] arr, int l, int r, Random rnd){
int p = l + rnd.nextInt(r-l+1); swap(arr, l , p);
int i = l+1 , j = r; while(true){
while(i <= j && arr[i].compareTo(arr[l]) < 0) i ++; while(j >= i && arr[j].compareTo(arr[l]) > 0) j --;
if(i >= j) break;
swap(arr, i , j); i ++; j --; } swap(arr, l , j); return j; }
public static <E extends Comparable<E>> void sort3ways(E[] arr){ Random rnd = new Random(); sort3ways(arr, 0, arr.length-1, rnd); }
private static <E extends Comparable<E>> void sort3ways(E[] arr, int l , int r, Random rnd){
if(l >= r) return;
int p = l + rnd.nextInt(r-l+1); swap(arr, l , p);
int lt = l , i = l + 1, gt = r + 1; while(i < gt){
if(arr[i].compareTo(arr[l])<0){ lt ++; swap(arr, i , lt ); i ++; } else if(arr[i].compareTo(arr[l])>0){ gt --; swap(arr, i, gt); } else{ i ++; } } swap(arr,l ,lt); sort3ways(arr, l , lt-1, rnd); sort3ways(arr, gt , r, rnd); }
private static <E> void swap(E[] arr, int i , int j){
E t = arr[i]; arr[i] = arr[j]; arr[j] = t; }
public static void main(String[] args) {
int n = 10000000; Integer[] arr = ArrayGenerator.generateRandomArray(n,n); Integer[] arr2 = Arrays.copyOf(arr, arr.length);
SortingHelper.sortTest("QuickSort", arr); SortingHelper.sortTest("QuickSort2", arr2);
arr = ArrayGenerator.generateOrderedArray(n); arr2 = Arrays.copyOf(arr, arr.length);
SortingHelper.sortTest("QuickSort", arr); SortingHelper.sortTest("QuickSort2", arr2);
arr = ArrayGenerator.generateRandomArray(n, 1); arr2 = Arrays.copyOf(arr, arr.length); Integer[] arr3 = Arrays.copyOf(arr, arr.length); SortingHelper.sortTest("QuickSort2", arr2); SortingHelper.sortTest("QuickSort3", arr3);
} }
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