Time: 3 ms (69.42%), Space: 58.2 MB (45.4%) - LeetHub

Author: furic

0020-valid-parentheses/0020-valid-parentheses.ts

@@ -1,20 +1,32 @@
-function isValid(s: string): boolean {
- const stack = [];
- for (let i = 0; i < s.length; i++) {
- if (s[i] === '(' || s[i] === '[' || s[i] === '{') {
- stack.push(s[i])
+const isValid = (s: string): boolean => {
+ const openBrackets: string[] = [];
+ const bracketPairs: Record<string, string> = {
+ ')': '(',
+ ']': '[',
+ '}': '{'
+ };
+ 
+ for (const char of s) {
+ const isOpenBracket = char === '(' || char === '[' || char === '{';
+ 
+ if (isOpenBracket) {
+ openBrackets.push(char);
  } else {
- if (stack.length === 0) {
+ // Closing bracket with no matching open bracket
+ if (openBrackets.length === 0) {
+ return false;
+ }
+ 
+ const lastOpenBracket = openBrackets.pop()!;
+ const expectedOpenBracket = bracketPairs[char];
+ 
+ // Mismatched bracket types
+ if (lastOpenBracket !== expectedOpenBracket) {
  return false;
  }
- const top = stack.pop();
- if (s[i] == ')' && top != '(') return false;
-
- if (s[i] == ']' && top != '[') return false;
-
- if (s[i] == '}' && top != '{') return false;
  }
  }
-
- return stack.length === 0;
+ 
+ // All brackets must be closed
+ return openBrackets.length === 0;
 };