二分查找

代码实现

  1. /**
  2.  * @author laoduan
  3.  * @create 2020-05-10-14:14
  4.  */
  6. //使用二分查找的前提是该数组是有序的
  7. public class BinarySearch {
  8.     public static void main(String[] args) {
  9.         int arr[]={1,8,10,89,1000,1234};
  10.         int resIndex = binarySearch(arr,0,arr.length-1,88);
  11.         System.out.println("resIndex="+resIndex);
  13.     }
  15.     public static int binarySearch(int[] arr,int left,int right,int findval){
  17.         if(left>right){
  18.             return -1;
  19.         }
  20.         int mid = (left+right)/2;
  21.         int midVal = arr[mid];
  24.         if(midVal<findval){
  25.             return binarySearch(arr,mid+1,right,findval);
  26.         }else if(midVal>findval){
  27.             return binarySearch(arr,left,mid-1,findval);
  28.         }
  29.         else{
  30.             return mid;
  31.         }
  32.     }
  33. }