堆排序

public class Heapsort {
	public static int[] Heap = { 10, 32, 1, 9, 5, 7, 12, 0, 4, 3 }; // 预设数据数组

	public static void buildMaxHeap(int[] heap, int start, int end) {
		if (heap == null || start < 0 || start >= end || heap.length <= start || heap.length < end) return;
		
		int child = 2 * start + 1;
		int parent = start;
		
		while (child < end) {
			if (child + 1 < end && heap[child] < heap[child + 1]) child ++;
			
			if (heap[parent] >= heap[child]) break;
			
			int temp = heap[parent];
			heap[parent] = heap[child];
			heap[child] = temp;
			
			parent = child;
			child = 2 * child + 1;
		}
	}
	
	public static void createHeap(int[] heap) {
		if (heap == null || heap.length == 0)return;
		
		for (int i = heap.length / 2 - 1 ; i >= 0; i --) {
			buildMaxHeap(heap, i, heap.length);
		}
		
		for (int i = heap.length - 1; i > 0; i --) {
			int temp = heap[0];
			heap[0] = heap[i];
			heap[i] = temp;
			buildMaxHeap(heap, 0, i);
		}
	}
	
	public static void main(String[] args) {
		System.out.println("排序前 ： ");
		
		for (int i = 0; i < Heap.length; i ++) {
			System.out.print(Heap[i] + " ");
		}
		
		System.out.println();
		
		createHeap(Heap);
		
		System.out.println("排序后 ： ");
		
		for (int i = 0; i < Heap.length; i ++) {
			System.out.print(Heap[i] + " ");
		}
		
	}
}