/**
* 快速排序3.0
* 1.0和2.0版本的时间复杂度都是O(N^2)
* 3.0版本时间复杂度是O(NlogN)
*/
public class QuickSort3 {
public static void main(String[] args) {
int[] array = {3,1,2,4,5,3,5};
QuickSort(array, 0, array.length - 1);
for (int i : array) {
System.out.println(i);
}
}
public static void QuickSort(int[] array, int left, int right){
if (left < right){
//随机将数组中一个数放在数组的最右侧
swap(array, left + (int) (Math.random() * (right - left + 1)), right);
int[] partition = partition(array, left, right);
QuickSort(array, left, partition[0] - 1);
QuickSort(array, partition[1] + 1, right);
}
}
public static int[] partition(int[] array,int left, int right){
int less = left - 1;
int more = right;
while (left < more){
if (array[left] < array[right]){
swap(array, ++less, left++);
}else if (array[left] > array[right]){
swap(array, --more, left);
}else {
left++;
}
}
swap(array, more, right);
return new int[]{less + 1, more};
}
public static void swap(int[] array, int a, int b){
if (a == b){
return;
}
array[a] = array[a] ^ array[b];
array[b] = array[a] ^ array[b];
array[a] = array[a] ^ array[b];
}
}