LeetCode #20 Valid Parentheses with JavaScript

Solution to LeetCode's 20. Valid Parentheses with JavaScript.

Solution

/**
 * @param {string} s
 * @return {boolean}
 */
const isValid = (s) => {
  const map = {
    "(": ")",
    "[": "]",
    "{": "}",
  };
  const stack = [];
  for (let i = 0; i < s.length; i++) {
    if (stack.length > 0 && map[stack[stack.length - 1]] === s[i]) {
      stack.pop();
    } else {
      stack.push(s[i]);
    }
  }
  return stack.length === 0;
};

• Time complexity: O(n)
• Space complexity: O(n)

1. save the target parentheses in an object with keys and values
2. add the string to the stack array in a for loop
3. if the closing parenthesis is a pair with the last value in the stack array, remove it from the stack array
4. return true if the stack array is finally empty, false if it remains