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20. Valid Parentheses Leetcode Problem Javascript Solution

20. Valid Parentheses
Easy
Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.
An input string is valid if:
  1. Open brackets must be closed by the same type of brackets.
  2. Open brackets must be closed in the correct order.
Note that an empty string is also considered valid.
Example 1:
Input: "()"
Output: true
Example 2:
Input: "()[]{}"
Output: true
Example 3:
Input: "(]"
Output: false
Example 4:
Input: "([)]"
Output: false
Example 5:
Input: "{[]}"
Output: true
var isValid = function(s) {
  const stack = [];
  const pairs = {
    '}':'{',
    ']':'[',
    ')':'('
  };
  for (const char of s) {
    const there = pairs[char];
    if (there) {
      if(stack.pop() !== there) {
        return false;
      }
    } else {
      stack.push(char);
    }
  }
  return stack.length <= 0;
}

console.log(isValid('{}()'));
Run the code: https://repl.it/@VinitKhandelwal/20-Leetcode-Javascript-Vaild-Parenthesis

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