'Single Element in s Sorted Array' solved

Author: kaidul

source-code/Serialize_and_Deserialize_BST.cpp

@@ -7,6 +7,7 @@
  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
  * };
  */
+// Any serialize-deserialize technique working for BT will work for BST because BST is a BT but may not the other way around
 class Codec {
     void preorder(TreeNode* root, string& data) {
         if(!root) return;

source-code/Single_Element_in_a_Sorted_Array.cpp

@@ -0,0 +1,21 @@
+class Solution {
+public:
+    int singleNonDuplicate(vector<int>& arr) {
+        int n = (int)arr.size();
+        int left = 0, right = n - 1;
+        while(left < right) {
+            int mid = left + (right - left) / 2;
+            if(arr[mid] != arr[mid - 1] and arr[mid] != arr[mid + 1]) {
+                return arr[mid];
+            }
+            
+            if((mid % 2 == 1 and arr[mid] == arr[mid - 1]) or
+                (mid % 2 == 0 and arr[mid] == arr[mid + 1])) {
+                left = mid + 1;
+            } else {
+                right = mid - 1;
+            }
+        }
+        return arr[left];
+    }
+};