feat: Add solution for valid-parentheses problem

Author: pragusga25

easy/valid-parentheses.test.ts

@@ -0,0 +1,42 @@
+// Problem: https://leetcode.com/problems/valid-parentheses/
+// Doc: https://leetcode.com/problems/valid-parentheses/solutions/5491623/efficient-solution-for-valid-parentheses/
+const isValid = (s: string): boolean => {
+  const stack: string[] = [];
+
+  const parClosedMap = {
+    ')': '(',
+    '}': '{',
+    ']': '[',
+  };
+
+  for (let i = 0; i < s.length; i++) {
+    const char = s[i];
+    if (!(char in parClosedMap)) {
+      stack.push(char);
+      continue;
+    }
+
+    const popped = stack.pop();
+    if (!popped) return false;
+    const opened = parClosedMap[char];
+    if (popped !== opened) return false;
+  }
+
+  return stack.length === 0;
+};
+
+describe('Valid Parentheses', () => {
+  it('should return true for valid parentheses', () => {
+    expect(isValid('()')).toBe(true);
+    expect(isValid('()[]{}')).toBe(true);
+    expect(isValid('{[]}')).toBe(true);
+    expect(isValid('([{}])')).toBe(true);
+  });
+
+  it('should return false for invalid parentheses', () => {
+    expect(isValid('(]')).toBe(false);
+    expect(isValid('([)]')).toBe(false);
+    expect(isValid('[')).toBe(false);
+    expect(isValid(']')).toBe(false);
+  });
+});