Add Order Agnostic Binary Search

Java/OrderAgnosticBS.java

@@ -0,0 +1,47 @@
+package com.viraj;
+
+public class OrderAgnosticBS {
+    public static void main(String[] args) {
+        int[] arr = {-18, -12, -4, 0, 2, 3, 4, 15, 16, 18, 22, 45, 89};
+        int target = 5;
+        int ans = orderAgnosticBS(arr,target);
+        System.out.println(ans);
+    }
+
+    static int orderAgnosticBS(int[] arr, int target){
+
+        int start = 0;
+        int end = arr.length - 1;
+
+        //find whether the array is sorted in ascending or descending.
+        boolean isAsc = arr[start] < arr[end];
+
+
+
+        while(start <= end){
+            //find the middle element
+            //int mid = (start + end) / 2; //might be possible that (start + end ) exceeds the range of int.
+            int mid = start + (end-start)/2;
+
+            if(arr[mid] == target) return mid;
+
+            if(isAsc){
+                if(target < arr[mid]){
+                    end = mid - 1;
+                }
+                else {
+                    start = mid+1;
+                }
+            }
+            else{
+                if(target > arr[mid]){
+                    end = mid - 1;
+                }
+                else {
+                    start = mid+1;
+                }
+            }
+        }
+        return -1;
+    }
+}