How to verify all matching Brackets

Question

Implement function verify(text) which verifies whether parentheses within text are correctly nested. You need to consider three kinds: (), [], <> and only these kinds. Examples:

verify("---(++++)----")  -> 1 
verify("") -> 1 
verify("before ( middle []) after ") -> 1  
verify(") (") -> 0 
verify("<(   >)") -> 0 
verify("(  [   <>  ()  ]  <>  )") -> 1 
verify("   (      [)") -> 0

I tried to do it as below but the interviewer told that there was an error and is giving me a second chance.

function verify(text) {
  const stack = [];
  for (const c of text) {
    if (c === '(') stack.unshift(')')
    else if (c === '[') stack.unshift(']')
    else if (c === '<') stack.unshift('>')
    else if (c === stack[0]) stack.shift()
    else if (c === ')' || c === ']' || c === '>') return 0
  }
  return 1
}


const test_inputs = ["---(++++)----", "", "before ( middle []) after ", ") (", "<( >)", "( [ <> () ] <> )", " ( [)"]
for (const i in test_inputs) {
  console.log(verify(i))
}

The output is:

1
1
1
1
1
1
1

Answer 1

We can use the pop and push functions of Array. When we encounter with '(', '[', '<' characters, we push to the stack. On the other hand, when we encounter ')', ']', '>', we pop the last element of stack. If we can't find the equivalents of these characters, we determine that the string is not valid. Finally, if there are no elements left in the stack, this means the string is valid.

function verify(text) {
    let stack = [];
    for (const c of text) {
        if (c === '(' || c == '[' || c == '<') {
            stack.push(c);
        } else if (c === ')' || c == ']' || c == '>') {
            if (stack.length == 0) {
                return 0;
            }
            const popValue = stack.pop();
            if (c === ')' && popValue != '(') {
                return 0;
            } else if (c === ']' && popValue != '[') {
                return 0;
            } else if (c === '>' && popValue != '<') {
                return 0;
            }
        }

    }

    if (stack.length > 0) {
        return 0;
    }

    return 1;
}