Create single-number-ii.cpp

Author: kamyu104

C++/single-number-ii.cpp

@@ -0,0 +1,17 @@
+// Time:  O(n)
+// Space: O(1)
+
+class Solution {
+public:
+    int singleNumber(vector<int>& nums) {
+        int one = 0, two = 0;
+
+        for (const auto& i : nums) {
+            int new_one = (~i & one) | (i & ~one & ~two);
+            int new_two = (~i & two) | (i & one);
+            one = new_one, two = new_two;
+        }
+
+        return one;
+    }
+};