Binary Search | Java implementation of recursive Binary Search ; Returns index of x if it is present in arr [ l . . r ] , else return - 1 ; If the element is present at the middle itself ; If element is smaller than mid , then it can only be present in left subarray ; Else the element can only be present in right subarray ; We reach here when element is not present in array ; Driver method to test above
class BinarySearch { int binarySearch ( int arr [ ] , int l , int r , int x ) { if ( r >= l ) { int mid = l + ( r - l ) / 2 ; if ( arr [ mid ] == x ) return mid ; if ( arr [ mid ] > x ) return binarySearch ( arr , l , mid - 1 , x ) ; return binarySearch ( arr , mid + 1 , r , x ) ; } return - 1 ; } public static void main ( String args [ ] ) { BinarySearch ob = new BinarySearch ( ) ; int arr [ ] = { 2 , 3 , 4 , 10 , 40 } ; int n = arr . length ; int x = 10 ; int result = ob . binarySearch ( arr , 0 , n - 1 , x ) ; if ( result == - 1 ) System . out . println ( " Element ▁ not ▁ present " ) ; else System . out . println ( " Element ▁ found ▁ at ▁ index ▁ " + result ) ; } }