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Nesting (Lesson 7)

Instructions​

A string S consisting of N characters is called properly nested if:

  • S is empty;
  • S has the form "(U)" where U is a properly nested string;
  • S has the form "VW" where V and W are properly nested strings.

For example, string "(()(())())" is properly nested but string "())" isn't.

Write a function:

function solution(S);

that, given a string S consisting of N characters, returns 1 if string S is properly nested and 0 otherwise.

For example, given S = "(()(())())", the function should return 1 and given S = "())", the function should return 0, as explained above.

Write an efficient algorithm for the following assumptions:

  • N is an integer within the range [0..1,000,000];
  • string S consists only of the characters "(" and/or ")".

Solution​

function solution(S) {
  const answer = [];

  for (let i = 0, sLength = S.length; i < sLength; i++) {
    const curBracket = S[i];

    if (curBracket === "(") {
      answer.push(curBracket);
    } else {
      const lastBracket = answer.pop();
      if (lastBracket !== "(") {
        return 0;
      }
    }
  }

References​