Valid Parentheses — Animation

Step through the stack-based solution. Edit the input, pick a variant, and watch each character processed.

SolutionWhen a closing bracket appears, pop the stack and check it equals the expected opener.Input stringOnly brackets — other characters follow the `else` branch.

Speed

Step 1 / 14…running

Input

([{}])

Stack (top on right)

empty

Action

Initialize empty stack.

Code

0function isValid(s) {
1  const map = { ')': '(', ']': '[', '}': '{' };
2  const stack = [];
3  for (const char of s) {
4    if (char in map) {
5      if (stack.pop() !== map[char]) return false;
6    } else {
7      stack.push(char);
8    }
9  }
10  return stack.length === 0;
11}