feat: Implement max and maxRange methods to find maximum element in full or partial array

🧠 Logic:
- `maxRange(arr, start, end)` finds the maximum value in a subarray from index `start` to `end`.
  - Handles edge cases: null array or invalid range (`start > end`) return -1.
- `max(arr)` finds the maximum element in the entire array.
  - Returns -1 if array is empty.
- Both methods use linear scan to compare and update max value.

Signed-off-by: Somesh diwan <[email protected]>

Author: Someshdiwan

Section9ArrayAB/Array IMP/Max.java

@@ -4,13 +4,11 @@ public static void main(String[] args) {
         System.out.println(maxRange(arr, 1, 3));
     }
 
-    // work on edge cases here, like array being null
+    // work on edge cases here, like an array being null.
     static int maxRange(int[] arr, int start, int end) {
-
         if (start > end) {
             return -1;
         }
-
         if (arr == null) {
             return -1;
         }