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
var isValid = function(s) {
const map = {
'(':')',
'{':'}',
'[':']',
}
let stack = []
for (let c of s) {
if (c in map){
stack.push(c)
} else if (map[stack.pop()] !== c) {
return false
}
}
return !stack.length
};