Add LC 1646 java solution (#142)

Author: Tahanima

Algorithms/Easy/1646_GetMaximumInGeneratedArray/Solution.java

@@ -0,0 +1,20 @@
+class Solution {
+    public int getMaximumGenerated(int n) {
+        int[] nums = new int[n + 1];
+        int max = 0;
+
+        for (int i = 0; i <= n; i++) {
+            if (i < 2) {
+                nums[i] = i;
+            } else if (i % 2 == 0) {
+                nums[i] = nums[i / 2];
+            } else {
+                nums[i] = nums[(i - 1) / 2] + nums[1 + (i - 1) / 2];
+            }
+
+            max = Math.max(max, nums[i]);
+        }
+
+        return max;
+    }
+}