Time: 11 ms (97.08%) | Memory: 24.9 MB (26.94%) - LeetSync

Author: sayandip20

540-single-element-in-a-sorted-array/single-element-in-a-sorted-array.cpp

@@ -0,0 +1,23 @@
+class Solution {
+public:
+    int singleNonDuplicate(vector<int>& arr) {
+        int n = arr.size();
+        if (n == 1) return arr[0];
+        if (arr[0] != arr[1]) return arr[0];
+        if (arr[n - 1] != arr[n - 2]) return arr[n - 1];
+        int low = 1, high = n - 2;
+        while (low <= high) {
+            int mid = low + (high - low) / 2;
+            if (arr[mid] != arr[mid + 1] && arr[mid] != arr[mid - 1]) {
+                return arr[mid];
+            }
+            if ((mid % 2 == 1 && arr[mid] == arr[mid - 1]) || (mid % 2 == 0 && arr[mid] == arr[mid + 1])) {
+                low = mid + 1;
+            }
+            else {
+                high = mid - 1;
+            }
+        }
+        return -1;
+    }
+};