堆排序算法
/**
* 堆排序
*
* @param array
* @return
*/
public static int[] heapSort(int[] array) {
int arrayLength = array.length;
for (int i = 0; i < arrayLength - 1; i++) {
buildMaxHeap(array, arrayLength - 1 - i);
swap(array, 0, arrayLength - 1 - i);
}
return array;
}
private static void swap(int[] data, int i, int j) {
int tmp = data[i];
data[i] = data[j];
data[j] = tmp;
}
private static void buildMaxHeap(int[] data, int lastIndex) {
for (int i = (lastIndex - 1) / 2; i >= 0; i--) {
int k = i;
while (k * 2 + 1 <= lastIndex) {
int biggerIndex = 2 * k + 1;
if (biggerIndex < lastIndex) {
if (data[biggerIndex] < data[biggerIndex + 1]) {
biggerIndex++;
}
}
if (data[k] < data[biggerIndex]) {
swap(data, k, biggerIndex);
k = biggerIndex;
} else {
break;
}
}
}
}
运行
/**
* 待排序的数组
*/
private static int[] array = {
12, 10, 5, 9, 5, 32, 16, 1, 9, 99, 80, 3, 18, 19, 20, 25, 7, 15
};
public static void main(String[] args) {
int[] result = SortUtils.heapSort(array.clone());
System.out.println(Arrays.toString(result));
}
输出
[1, 3, 5, 5, 7, 9, 9, 10, 12, 15, 16, 18, 19, 20, 25, 32, 80, 99]
