排序总结一

1.冒泡排序:

public void bubbleSort() {
		int i, j;
		for (i = 0; i < a.length - 1; i++) {
			for (j = a.length - 1; j > i; j--) {
				if (a[j] < a[j - 1]) {
					temp = a[j - 1];
					a[j - 1] = a[j]; 
					a[j] = temp;
				}
			}
		}
}

冒泡排序改进:

public void bubbleSort3() {
		int i,j;
		int exchange= 0; //标记是否交换
		for (i = 0; i < a.length - 1; i++) {
			exchange = 0;
			for (j = a.length - 1; j > i; j--) {
				if (a[j] < a[j - 1]) {
					temp = a[j - 1];
					a[j - 1] = a[j];
					a[j] = temp;
					exchange = 1;   //标记交换
				}
			}
			if(exchange != 1) {
				break;
			}
		}
	}

2.直接插入排序:

public void directSort() {
		int i, j;
		for (i = 1; i < a.length; i++) {
			if (a[i] < a[i - 1]) {
				temp = a[i];
				for (j = i - 1; j >= 0 && a[j] > temp; j--) {
					a[j + 1] = a[j];
				}
				a[j + 1] = temp;
			}
		}
		for (i = 0; i < a.length; i++) {
			System.out.println(a[i]);
		}
	}

3.希尔排序:

基本思想:先将整个待排序记录序列按增量ｄ分割成若干个子序列分别进行直接插入排序,然后再用一个较小的增量ｄ进行再次排序,以当增量减至1时,整个序列中的记录已"基本有序"时,再对全体记录进行一次直接插入排序.

public void shellSort() {
		int count = 0;
		int j;
		for (int d = n / 2; d > 0; d /= 2) {
			for (int i = d; i < n; i++) {
				temp = a[i];
				for (j = i - d; (j >= 0 && temp < a[j]); j = j - d) {
					a[j + d] = a[j];
				}
				a[j + d] = temp;
			}
			count++;
			System.out.print("第" + count + "次排序结果:");
			for (int i = 0; i < n; i++) {
				System.out.print(a[i] + "");
			}
			System.out.println();
		}
	}

5.快速排序

// 快速排序
	public void quickSort(int[] a, int lo, int hi) {
		if (lo < hi) {
			int k = partition(a, lo, hi);
			quickSort(a, lo, k - 1);
			quickSort(a, k + 1, hi);
		}
		for (int i = 0; i < n; i++) {
			System.out.print(a[i]);
		}
		System.out.println();
	}

	private int partition(int[] a, int lo, int hi) {
		int i = lo - 1;
		int key = a[hi];// 取最后一个元素做为关键值
		int temp;
		for (int j = lo; j < hi; j++) {
			if (a[j] <= key) {
				i++;
				temp = a[j];
				a[j] = a[i];
				a[i] = temp;
			}
		}
		a[hi] = a[i + 1];
		a[i + 1] = key;
		return i + 1;
	}

public void quickSort2(int[] a, int lo, int hi) {
		if (lo < hi) {
			int k = partition2(a, lo, hi);
			quickSort2(a, lo, k - 1);
			quickSort2(a, k + 1, hi);
		}

	}

	private int partition2(int[] a, int lo, int hi) {
		int key = a[hi]; // 取最后一个元素
		while (lo < hi) {
			while (lo < hi && a[lo] <= key) {
				lo++;
			}
			if (lo < hi) {
				a[hi--] = a[lo];
			}
			while (lo < hi && a[hi] >= key) {
				hi--;
			}
			if (lo < hi) {
				a[lo++] = a[hi];
			}
		}
		a[hi] = key;
		return hi;
	}