From 455316f1396e98e46fdd43b7fad479b68da1eac0 Mon Sep 17 00:00:00 2001
From: verdant <im@verdant.ee>
Date: Tue, 30 Jun 2026 12:11:38 +0800
Subject: Move from GitHub

---
 leetcode/0020/main.c | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100644 leetcode/0020/main.c

(limited to 'leetcode/0020/main.c')

diff --git a/leetcode/0020/main.c b/leetcode/0020/main.c
new file mode 100644
index 0000000..cf3a4dd
--- /dev/null
+++ b/leetcode/0020/main.c
@@ -0,0 +1,43 @@
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+
+bool isValid(char *s) {
+  int n = strlen(s);
+  if (n < 2)
+    return false;
+
+  char *stack = (char *)malloc(sizeof(char) * (n + 1));
+  int top = -1;
+
+  for (int i = 0; i < n; i++) {
+    char ch = s[i];
+
+    if (ch == '(' || ch == '[' || ch == '{') {
+      stack[++top] = ch;
+    } else {
+      if (top == -1) {
+	return false;
+      }
+
+      char topChar = stack[top--];
+
+      if (ch == ')' && topChar != '(') {
+	free(stack);
+	return false;
+      }
+      if (ch == ']' && topChar != '[') {
+	free(stack);
+	return false;
+      }
+      if (ch == '}' && topChar != '{') {
+        free(stack);
+        return false;
+      }
+    }
+  }
+
+  bool result = (top == -1);
+  free(stack);
+  return result;
+}
-- 
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