Create minimum-add-to-make-parentheses-valid.cpp

Author: kamyu104

C++/minimum-add-to-make-parentheses-valid.cpp

@@ -0,0 +1,17 @@
+// Time:  O(n)
+// Space: O(1)
+
+class Solution {
+public:
+    int minAddToMakeValid(string S) {
+        int add = 0, bal = 0;
+        for (const auto& c : S) {
+            bal += c == '(' ? 1 : -1;
+            if (bal == -1) {
+                ++add;
+                ++bal;
+            }
+        }
+        return add + bal;
+    }
+};