Create minimum-insertions-to-balance-a-parentheses-string.cpp

Author: kamyu104

C++/minimum-insertions-to-balance-a-parentheses-string.cpp

@@ -0,0 +1,25 @@
+// Time:  O(n)
+// Space: O(1)
+
+class Solution {
+public:
+    int minInsertions(string s) {
+        int add = 0, bal = 0;
+        for (const auto& c: s) {
+            if (c == '(') {
+                if (bal % 2 > 0) {
+                    ++add;  // add ')' to make sure consecutive ')'
+                    --bal;
+                }
+                bal += 2;
+            } else {
+                --bal;
+                if (bal < 0) {
+                    ++add;  // add '('
+                    bal += 2;
+                }
+            }
+        }
+        return add + bal;
+    }
+};