Leetcode•Apr 14, 2025
Valid Parentheses
Hazrat Ali
Leetcode
Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.
An input string is valid if:
- Open brackets must be closed by the same type of brackets.
- Open brackets must be closed in the correct order.
- Every close bracket has a corresponding open bracket of the same type.
Example 1:
Input: s = "()"
Output: true
Example 2:
Input: s = "()[]{}"
Output: true
Example 3:
Input: s = "(]"
Output: false
Example 4:
Input: s = "([])"
Output: true
Solution
/**
* @param {string} s
* @return {boolean}
*/
const isValid = s => {
const stack = [];
for (let i = 0; i < s.length; i++) {
if (s[i] === '(') {
stack.push(')');
} else if (s[i] === '[') {
stack.push(']');
} else if (s[i] === '{') {
stack.push('}');
} else if (stack.length === 0 || stack.pop() !== s[i]) {
return false;
}
}
return stack.length === 0;
};