public class arrayBinary{ public static int bsearch(int array[],int value){ boolean found=false; int high=array.length-1; int low=0; int cnt=0;//查找步数 int mid=(high+low)/2; System.out.println("Looking for "+value); while(!found&&(high>=low)){ System.out.print(" Low "+low+" Mid "+mid); System.out.print(" High "+high); if(value==array[mid]) found=true; else if(value< array[mid]) high=mid-1; else low=mid+1; mid=(high+low)/2; cnt++; } System.out.println(); System.out.println("Steps "+cnt); return((found)?mid:-1); } public static void main(String[] args){ int array[]=new int[100]; for(int i=0;i< array.length;i++) array[i]=i; System.out.println("Resulte "+bsearch(array,67)); System.out.println("Resulte "+bsearch(array,33)); System.out.println("Resulte "+bsearch(array,1)); System.out.println("Resulte "+bsearch(array,1001)); } }程序结果:
C:\java>javac arrayBinary.java
C:\java>java arrayBinary
Looking for 67
Low 0 Mid 49 High 99 Low 50 Mid 74 High 99 Low 50 Mid 61 High 73 Low 62 Mid 67 High 73
Steps 4
Resulte 67
Looking for 33
Low 0 Mid 49 High 99 Low 0 Mid 24 High 48 Low 25 Mid 36 High 48 Low 25 Mid 30 High 35 Low 31 Mid 33 High 35
Steps 5
Resulte 33
Looking for 1
Low 0 Mid 49 High 99 Low 0 Mid 24 High 48 Low 0 Mid 11 High 23 Low 0 Mid 5 High
10 Low 0 Mid 2 High 4 Low 0 Mid 0 High 1 Low 1 Mid 1 High 1
Steps 7
Resulte 1
Looking for 1001
Low 0 Mid 49 High 99 Low 50 Mid 74 High 99 Low 75 Mid 87 High 99 Low 88 Mid 93
High 99 Low 94 Mid 96 High 99 Low 97 Mid 98 High 99 Low 99 Mid 99 High 99
Steps 7
Resulte -1
C:\java>
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