随着校招的临近 算法是校招中很重要的一个部分 总结了常见几种排序算法，各种算法的时间复杂度和空间复杂度大家也需要多了解下

package com.huwei.sort;

/**
 * 各种排序算法
 * 
 * @author huwei
 * 
 */
public class Sort {
	public static void main(String[] args) {
		int[] a = { 60, 57, 89, 47, 57, 98, 45, 35, 73 };
		Sort sort = new Sort();
		sort.quickSort(a);
		for (int i = 0; i < a.length; i++) {
			System.out.print(" " + a[i] + " ");
		}
	}

	/**
	 * 插入排序
	 * 
	 * @param data
	 */
	public void insertSort(int[] data) {
		for (int i = 1; i < data.length; i++) {
			for (int j = i; (j > 0) && (data[j] < data[j - 1]); j--) {
				swap(data, j, j - 1);
			}
		}
	}

	/**
	 * 冒泡排序
	 * 
	 * @param data
	 */
	public void bubbleSort(int[] data) {
		for (int i = 0; i < data.length; i++) {
			for (int j = data.length - 1; j > i; j--) {
				if (data[j] < data[j - 1]) {
					swap(data, j, j - 1);
				}
			}
		}

	}

	/**
	 * 选择排序
	 * 
	 * @param data
	 */
	public void selectSort(int[] data) {
		for (int i = 0; i < data.length; i++) {
			int lowIndex = i;
			for (int j = data.length - 1; j > i; j--) {
				if (data[j] < data[lowIndex]) {
					lowIndex = j;
				}
			}
			swap(data, i, lowIndex);
		}
	}

	/**
	 * shell排序
	 * 
	 * @param data
	 */
	public void shellSort(int[] data) {
		for (int i = data.length / 2; i > 2; i /= 2) {
			for (int j = 0; j < i; j++) {
				insertSort(data, j, i);
			}
		}
		insertSort(data, 0, 1);// 最后进行一次插入排序
	}

	private void insertSort(int[] data, int start, int inc) {
		for (int i = start + inc; i < data.length; i += inc) {
			for (int j = i; (j >= inc) && (data[j] < data[j - inc]); j -= inc) {
				swap(data, j, j - inc);
			}
		}
	}

	/**
	 * 快速排序 重点
	 * 
	 * @param data
	 */
	public void quickSort(int[] data) {
		quickSort(data, 0, data.length - 1);
	}

	private void quickSort(int[] data, int i, int j) {
		int pivotIndex = (i + j) / 2;
		// swap
		swap(data, pivotIndex, j);

		int k = partition(data, i - 1, j, data[j]);
		swap(data, k, j);
		if ((k - i) > 1)
			quickSort(data, i, k - 1);
		if ((j - k) > 1)
			quickSort(data, k + 1, j);

	}

	private int partition(int[] data, int l, int r, int pivot) {
		do {
			while (data[++l] < pivot)
				;
			while ((r != 0) && data[--r] > pivot)
				;
			swap(data, l, r);
		} while (l < r);
		swap(data, l, r);
		return l;
	}

	/**
	 * 归并排序
	 * 
	 * @param data
	 */
	public void mergeSort(int[] data) {
		int[] temp = new int[data.length];
		mergeSort(data, temp, 0, data.length - 1);
	}

	private void mergeSort(int[] data, int[] temp, int l, int r) {
		int mid = (l + r) / 2;
		if (l == r)
			return;
		mergeSort(data, temp, l, mid);
		mergeSort(data, temp, mid + 1, r);
		for (int i = l; i <= r; i++) {
			temp[i] = data[i];
		}
		int i1 = l;
		int i2 = mid + 1;
		for (int cur = l; cur <= r; cur++) {
			if (i1 == mid + 1)
				data[cur] = temp[i2++];
			else if (i2 > r)
				data[cur] = temp[i1++];
			else if (temp[i1] < temp[i2])
				data[cur] = temp[i1++];
			else
				data[cur] = temp[i2++];
		}
	}

	/**
	 * 堆排序
	 * 
	 * @param data
	 */
	public void heapSort(int[] data) {
		MaxHeap h = new MaxHeap();
		h.init(data);
		for (int i = 0; i < data.length; i++)
			h.remove();
		System.arraycopy(h.queue, 1, data, 0, data.length);
	}

	private static class MaxHeap {

		void init(int[] data) {
			this.queue = new int[data.length + 1];
			for (int i = 0; i < data.length; i++) {
				queue[++size] = data[i];
				fixUp(size);
			}
		}

		private int size = 0;

		private int[] queue;

	/*	public int get() {
			return queue[1];
		}*/

		public void remove() {
			swap(queue, 1, size--);
			fixDown(1);
		}

		// fixdown
		private void fixDown(int k) {
			int j;
			while ((j = k << 1) <= size) {
				if (j < size && queue[j] < queue[j + 1])
					j++;
				if (queue[k] > queue[j]) // 不用交换
					break;
				swap(queue, j, k);
				k = j;
			}
		}

		private void fixUp(int k) {
			while (k > 1) {
				int j = k >> 1;
				if (queue[j] > queue[k])
					break;
				swap(queue, j, k);
				k = j;
			}
		}

	}

	public static void swap(int[] data, int i, int j) {
		int temp = data[i];
		data[i] = data[j];
		data[j] = temp;
	}
}