排序及二分查找

/**
 * @className:TwoDivide.java
 * @classDescription:排序和二分查找
 * @author:jiangmianyue
 * @createTime:2011-6-15
 */

public class TwoDivide {

	/**
	 * 冒泡排序
	 * 
	 * @author jiangmianyue
	 * @createTime 2011-6-15
	 * @param args
	 */
	public static void main(String[] args) {
		int[] aa = new int[] { 1, 8, 18, 38, 98, 218, 982, 1189 };

		// 冒泡排序
		System.out.println("排序前");
		for (int i = 0; i < aa.length - 1; i++) {
			System.out.println(aa[i]);
		}
		for (int i = 1; i < aa.length; i++) {
			for (int j = 0; j < aa.length; j++) {
				if (aa[i] < aa[j]) {
					aa[i] = aa[i] + aa[j];
					aa[j] = aa[i] - aa[j];
					aa[i] = aa[i] - aa[j];
				}
			}
		}
		System.out.println("排序后");
		for (int i = 0; i < aa.length; i++) {
			System.out.println(aa[i]);
		}

		System.out.println("第二种排序");
		for(int i = 0; i < aa.length - 1; i++){
			for(int j = 0; j < aa.length - i -1; j ++){
				if (aa[j] < aa[j + 1]){
					aa[j] = aa[j] + aa[j + 1];
					aa[j + 1] = aa[j] - aa[j + 1];
					aa[j] = aa[j] - aa[j + 1];
				}
			}
		}
		for (int i = 0; i < aa.length; i++) {
			System.out.println(aa[i]);
		}
		System.out.println(doOrder(aa, 100));

	}

	/**
	 * 二分查找
	 * 
	 * @author jiangmianyue
	 * @createTime 2011-6-15
	 * @param aa
	 *            数组
	 * @param a
	 *            要查找的值
	 * @return 返回在数据中的位置
	 */
	public static int doOrder(int[] aa, int a) {
		int low = 0; // 数组的最小值小标
		int hight = aa.length - 1; // 数组的最大值下标
		// while条件是当low小于等于hight时执行
		while (low <= hight) {
			// 取数组的中间下标
			int middle = (hight + low) / 2;
			if (a < aa[middle]) {
				// 当要查找的值小于中间值的时候把中间值减1赋值给最大值
				hight = middle - 1;
			} else if (a > aa[middle]) {
				// 当要查找的值大于中间值的时候把中间值加1赋值给最小值
				low = middle + 1;
			} else {
				// 最后得出的中间值为要的下标值
				return middle;
			}
		}
		return -1;
	}
}

 

 

评论

1 楼 xuehanxin 2011-07-19  

里面有个概念性错误。。。看谁第一个发现