2015 where to go programming question 1

[Programming questions] two-point search

For an ordered array, we usually use a binary lookup to locate an element, write a binary lookup algorithm, and find the specified element in the array.

Given an integer array a and its size n, given the element to find Val, return its position in the array (starting at 0), or 1 if the element does not exist. If the element appears more than once, return to the first occurrence of the position.

Test examples:

[1,3,5,7,9],5,3

Returns: 1

The code is as follows:

Import java.util.*;p Ublic class BinarySearch {public    int getPos (int[] A, int n, int val) {        //write code here
   
    return BinarySearch (a,0,n-1,val);    }        int BinarySearch (int[] a,int begin,int end,int val) {        int mid=begin+ (end-begin)/2;        while (begin<=end) {            if (Val==a[mid]) {                int ret=mid;                while (ret-1>=0) {                    if (a[ret-1]==val)                        ret--;                    else break;                }                return ret;            }            else if (Val<a[mid]) {               return BinarySearch (A,begin,mid-1, Val);            } else{                begin=mid+1;               Return  BinarySearch (A,mid+1,end, Val);                            }        }         return-1;}    }
   

　　

2015 where to go programming question 1