diff --git a/src/com/gatsby/_921MinimumAddToMakeParenthesesValid.java b/src/com/gatsby/_921MinimumAddToMakeParenthesesValid.java
new file mode 100644
index 0000000..27d81c8
--- /dev/null
+++ b/src/com/gatsby/_921MinimumAddToMakeParenthesesValid.java
@@ -0,0 +1,29 @@
+package com.gatsby;
+
+/**
+ * @ClassName: _921MinimumAddToMakeParenthesesValid
+ * @Description: 921. Minimum Add to Make Parentheses Valid
+ * @author: Gatsby
+ * @date: 2022/7/29 12:02
+ */
+
+public class _921MinimumAddToMakeParenthesesValid {
+    public int minAddToMakeValid(String s) {
+        int left = 0;
+        int count = 0;
+        for (int i = 0; i < s.length(); ++i) {
+            if (s.charAt(i) == ')') {
+                if (left == 0) {
+                    count++;
+                } else if (left > 0) {
+                    left--;
+                }
+            } else {
+                left++;
+            }
+        }
+        return left + count;
+    }
+}
+
+