20. Valid Parentheses

const map = {
   "(": ")",
   "{": "}",
   "[": "]"
}
 
function isValid(s: string): boolean {
   let stack = [];
   for(let i = 0; i < s.length; i++) {
       const c = s[i]
       if(c in map) {
           stack.push(c)
       } else {
           if(stack.length === 0) {
               return false;
           }
           let open = stack.pop();
           if(map[open] !== c) {
               return false;
           }
       }
   }
   return stack.length === 0;    
};