Binary Search implementation via java

Please see the below java source code for binary search implementation

public class Main {
public static void main (String args) {

int x= {1,2,3,4,5,6,7,8,9,10,11};
int y=binarySearch(x,11);
System.out.println(y);


}public static int binarySearch(int arr,int value) {
int searchedIndex = -1;
int first=0;
**int last=arr.length-1;**
int mid;

while(first<=last) {
mid=(first+last)/2;

if(arr[mid]==value) {
searchedIndex=mid;
break;
}else {
if(value<arr[mid]) {
last=mid-1;
}else {
first=mid+1;
}
}
}




return searchedIndex;
}


}


int last=arr.length-1 is -1 compulsory or not.I feel that code works fine either last=arr.length-1. If its compulsory please explain why.

array[0]

array[1]

array[4]

2 Answers
2

Arrays already have a method binarySearch you can just use :

binarySearch

int x = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11};
int r = Arrays.binarySearch(x, 11);


Yes it’s true but is it compulsory to include -1 . When we include-1 ,mid calculation value change automatically

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