堆排序heapSort

堆排序

/**
 *堆排序：是利用完全二叉树特性的一种选择排序。
 *时间复杂度O(nlog(2)n),空间复杂度O(1)
 *堆：根节点最大/小,对序列用于多次求极值的应用问题。如优先队列、Huffman、Prim、Kruskal、Dijkstra、Floyd等算法
 * @author 
 *
 */
public class heapSort {
	public static void heapSort(int[] keys){
		heapSort(keys,true);
	}
	public static void heapSort(int[] keys,boolean minheap){
		for(int i=keys.length/2-1;i>=0;i--) sift(keys,i,keys.length-1,minheap);//创建最小/最大堆，根结点值最小/大
		for(int i=keys.length-1;i>0;i--){ //将最小/最大值交换到最后，再调整成最小/最大堆
			swap(keys,0,i);
			sift(keys,0,i-1,minheap);
		}
	}
	private static void swap(int[] keys,int i,int j){
		int temp = keys[i];
		keys[i] = keys[j];
		keys[j] = temp;
	}
	
	private static void sift(int[] keys,int parent,int end,boolean minheap){//将以parent为根的子树调整为最小/最大堆，子序列范围parent~end
		int child = parent*2+1;
		int value = keys[parent];
		while(child<=end){ //沿孩子结点向下筛选
			if(childkeys[child+1]:keys[child]keys[child]:value