Solution for - CodeSignal - Reverse In Parentheses

gistfile1.txt

// 1. Find the pairs of parentheses
function getStartAndEndIndexes(inputString) {
  const regularExpression = /\([a-zA-Z]*?\)/;
  const execData = regularExpression.exec(inputString);
  if(!execData) {
    return null;
  }
  const startIndex = execData.index;
  const endIndex = execData.index + execData[0].length - 1;
  return {startIndex, endIndex}
}

// 2. Find the part of the string we need to reverse
function reverseParentheses(startIndex, endIndex, inputString) {
  // before the parenthesis
  const startSegmant = inputString.substring(0, startIndex);
  // the parenthesis
  const parenthesisSegmant = 
  inputString.substring(startIndex +1, endIndex);
  // after the parenthesis
  const endSegmant = 
  inputString.substring(endIndex + 1, inputString.length);
  return startSegmant + reverse(parenthesisSegmant) + endSegmant;
}

// 3. Reverse the string
function reverse(string) {
  return string.split('').reverse().join('');
}

// 4. Repeat until all parentheses are replaced
function reverseInParentheses(inputString) {
  let indexes = getStartAndEndIndexes(inputString);
  while(indexes) {
    const {startIndex, endIndex} = indexes; 
    const newString = 
    reverseParentheses(startIndex, endIndex, inputString);
    inputString = reverseInParentheses(newString);
    indexes = getStartAndEndIndexes(inputString);
  }
  return inputString;
}

Solution for Swift

func solution(inputString: String) -> String {
var result = ""
var stack = String
for letter in inputString {
if letter == "(" {
stack.append("")
} else if letter == ")" {
guard let last = stack.popLast() else { continue }
let reversedString = String(last.reversed())
if let lastStack = stack.last {
stack[stack.count - 1] = lastStack + reversedString
} else {
result += reversedString
}
} else if let lastStack = stack.last {
stack[stack.count - 1] += String(letter)
} else {
result += String(letter)
}
}
return result
}