Published Nov 30, 2021
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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.
Input: s = "()"
Output: true
Input: s = "()[]{}"
Output: true
Input: s = "(]"
Output: false
Input: s = "([)]"
Output: false
Input: s = "{[]}"
Output: true
- 1 <= s.length <= 104
- s consists of parentheses only '()[]{}'.
function isValid(s: string): boolean {
if(s.length % 2 === 1) return false;
const stack = []
const leftBrackets = ['(', '[', '{']
for(let p of s) {
// push to stack if it is left brackets
if(leftBrackets.includes(p)) {
stack.push(p)
} else {
// pop if it is right brackets and do order check
const current = stack.pop()
if(!(
(p === ')' && current === '(') ||
(p === ']' && current === '[' ) ||
(p === '}' && current === '{')
)
){
return false;
}
}
}
// there maybe only left brackets
return stack.length === 0;
};