堆排序java实现

堆排序实现

public class Heap {
	
	private static int heapSize = 0;

	public static void MAX_HEAPIFY(int[] A, int i) {
		int l = 2 * i ;
		int r = 2 * i + 1;
		int largest = 0;
		if (l <= heapSize && A[l-1] > A[i-1]) {
			largest = l;
		} else {
			largest = i;
		}
		if (r <= heapSize && A[r-1] > A[largest-1]) {
			largest = r;
		}
		if (largest != i) {
			int temp = A[i-1];
			A[i-1] = A[largest-1];
			A[largest-1] = temp;
			MAX_HEAPIFY(A, largest);
		}
	}

	public static void Build_MAX_HEAPIFY(int[] A) {
		heapSize = A.length;
		int half =A.length / 2;
		
		for (int i = half; i > 0; i--) {
			MAX_HEAPIFY(A, i);
		}
		// for(int j=0,leg=A.length; j<leg; j++){
		// System.out.println(A[j]);
		// }
	}

	public static void HEAPSORT(int[] A) {
		Build_MAX_HEAPIFY(A);
		for (int i = A.length; i >1; i--) {
			int temp = A[0];
			A[0] = A[i-1];
			A[i-1] = temp;
			heapSize--;
			MAX_HEAPIFY(A, 1);
		}
	}

	public static void main(String[] args) {

		int[] a = { 17, 8, 45, 84, 2, 94 };
		HEAPSORT(a);
		for (int i = 0; i < a.length; i++) {
			System.out.println(a[i]);
		}

	}

}