java程序中“两分法”查找数据
package Daniel;import java.util.Scanner;public class DoSearch {public static int bisSearch(int target){int[] a={2,3,5,7,12,15,18,36,45,67,74,87,88};int btm=0;int top=a.length;int mid=(btm+top)/2;while(a[mid]!=target){int old_mid = mid;if(a[mid]>target){top=mid;}else{btm=mid;}mid=(btm+top)/2;int new_mid=mid;if(old_mid==new_mid){return -1;}}return mid;}public static void main(String[] args) {Scanner sc=new Scanner(System.in);System.out.println("请输入你想查找的数： ");int a=sc.nextInt();int index= bisSearch(a);System.out.println(index);if (index==-1){System.out.println("序列中没有您要查找的数，请确认输入正确。");}else{System.out.println("所查找的数所在位置为：第"+(index+1)+"位");}}}?
这里关键是while(){}循环语句的使用：
while(a[mid]!=target){int old_mid = mid;if(a[mid]>target){top=mid;}else{btm=mid;}mid=(btm+top)/2;int new_mid=mid;if(old_mid==new_mid){return -1;}?
这里 mid的值 不断的改变 所以a[mid]不断的变化...来促使while（）{}的循环和终止... index是一串有序的数值..
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