二分法查找

import java.util.Arrays;
/**
测试二分法查找
*/
public class TestBinarySearch {
  public static void main(String[] args) {
      int[] arr = {30, 20, 50, 10, 80, 9, 7, 12, 100, 40, 8};
      Arrays.sort(arr);
      
      System.out.println(Arrays.toString(arr));
      System.out.println(myBinarySearch(arr, 40));
      
  }
   public static int myBinarySearch(int[] arr, int value) {
      int low = 0;
      int high = arr.length-1;
      
      while(low <= high) {
          int mid = (low+high)/2;
          
          if(value == arr[mid]) {
              return mid;
          }
          
          if(value > arr[mid]) {
              low = mid+1;
          }
          
          if(value < arr[mid]) {
              high = mid-1;
          }            
      }
      return -1;      //没有找到
  }
  
 
}