feat: add TypeScript solution for Valid Parentheses (practice1)

solutions/typescript/practice1.ts

@@ -0,0 +1,49 @@
+// Problem: Valid Parentheses
+// Source: https://leetcode.com/problems/valid-parentheses/
+// Note: Use an array as a stack and a lookup object to match closing brackets
+// Time: O(n), Space: O(n)
+
+// A string of brackets is valid when every closing bracket matches the most
+// recent unmatched opening bracket. That "most recent" rule is exactly what a
+// stack gives you, so this is a port of solutions/python/practice410.py with
+// TypeScript type annotations added to the function and its data structures.
+function isValid(s: string): boolean {
+  const matchingOpen: Record<string, string> = {
+    ")": "(",
+    "]": "[",
+    "}": "{",
+  };
+  const stack: string[] = [];
+
+  for (const char of s) {
+    if (Object.hasOwn(matchingOpen, char)) {
+      if (stack.length === 0 || stack.pop() !== matchingOpen[char]) {
+        return false;
+      }
+    } else {
+      stack.push(char);
+    }
+  }
+
+  return stack.length === 0;
+}
+
+const cases: Array<[string, boolean]> = [
+  ["()", true],
+  ["()[]{}", true],
+  ["(]", false],
+  ["([])", true],
+  ["([)]", false],
+  ["{[]}", true],
+  ["", true],
+  ["(", false],
+  ["(((((((((())))))))))", true],
+];
+
+for (const [value, expected] of cases) {
+  if (isValid(value) !== expected) {
+    throw new Error(`Failed for input: ${value}`);
+  }
+}
+
+console.log(`All ${cases.length} test cases passed!`);