排序算法总结

标签：java算法   排序算法   

package 排序算法;

/**
 * 1.选择排序 
 * 2.插入排序 
 * 3.归并排序 
 * 4.快速排序
 * 
 * @author Administrator
 * 
 */
public class 四种排序算法 {

	public static void main(String[] args) {
		int[] arr = { 2, 5, 6, 7, 4, 3, 1, 1, 3, 4, 5, 1, 3, 6, 3 };
		// selectSort(arr);
		// insertedSort(arr);
		// mergeSort(arr, 0, arr.length - 1);
		quickSort(arr, 0, arr.length - 1);
		out(arr);
	}

	// 输出
	public static void out(int[] arr) {
		for (int e : arr)
			System.out.print(e + ",");
	}

	// 1.选择排序
	public static void selectSort(int[] a) {
		for (int i = 0; i < a.length; i++)
			for (int j = i + 1; j < a.length; j++) {
				int key = a[i];
				if (key > a[j]) {
					a[i] = a[j];
					a[j] = key;
				}
			}
	}

	// 2.插入排序
	public static void insertedSort(int[] a) {

		for (int i = 1; i < a.length; i++) {

			int key = a[i];
			int j = i - 1;
			while (j >= 0 && key < a[j]) {
				a[j + 1] = a[j];
				a[j] = key;

				j--;
			}
		}
	}

	// 3.归并排序(分治法)
	public static void mergeSort(int[] a, int low, int high) {
		if (low < high) {

			int mid = (low + high) / 2;

			// 递归到最小原子
			mergeSort(a, low, mid);
			mergeSort(a, mid + 1, high);
			// 合并数组
			mergeArray(a, low, mid, high);
		}
	}

	// 合并数组
	private static void mergeArray(int[] a, int low, int mid, int high) {
		int N = high - low;
		int[] temp = new int[N + 1];

		int i = low, j = mid + 1;
		int m = mid, n = high;
		int k = 0;

		while (i <= m && j <= n)
			temp[k++] = (a[i] < a[j] ? a[i++] : a[j++]);

		while (i <= m)
			temp[k++] = a[i++];

		while (j <= n)
			temp[k++] = a[j++];

		for (i = 0; i < k; i++)
			a[low + i] = temp[i];
	}

	// 4.快速排序(分治法)
	public static void quickSort(int[] a, int low, int high) {
		if (low < high) {
			int r = adjustArray(a, low, high);
			quickSort(a, low, r - 1);
			quickSort(a, r + 1, high);
		}

	}

	// 提取数组中的首个元素，分割。小的元素放在<strong>标志</strong>的左边，比
	// 标志大的元素放在其右边，最后返回标志元素的位置
	private static int adjustArray(int[] a, int low, int high) {
		int i = low, j = high;
		int spcValue = a[low];

		while (i < j) {

			while (a[j] >= spcValue && i < j)
				j--;
			if (a[j] < spcValue)
				a[i++] = a[j];

			while (a[i] <= spcValue && i < j)
				i++;
			if (a[i] > spcValue)
				a[j--] = a[i];
		}
		a[i] = spcValue;
		return i;
	}
}

排序算法总结

标签：java算法   排序算法   

原文地址：http://blog.csdn.net/u010218226/article/details/45418799