Added day11 solution

Author: avidLearnerInProgress

30-days-of-code-may/11.singleElementInSortedArray.cpp

@@ -0,0 +1,22 @@
+class Solution {
+public:
+    int singleNonDuplicate(vector<int>& nums) {
+        
+        int start = 0, end = nums.size() - 1, mid;
+        
+        while(start < end){
+            mid = start + (end - start) / 2;
+            
+            if(mid % 2 == 0){
+                if(nums[mid] == nums[mid+1]) start = mid + 2;
+                else if(nums[mid] == nums[mid-1]) end = mid - 2;
+                else return nums[mid];
+            }
+            else{
+                if(nums[mid] == nums[mid-1]) start = mid + 1;
+                if(nums[mid] == nums[mid+1]) end = mid - 1;
+            }
+        }
+        return nums[start];
+    }
+};