Feature #9: Validate Program Brackets

Sumit Rawal answered on September 6, 2023 Popularity 1/10 Helpfulness 1/10

answer Feature #9: Validate Program Brackets

Feature #9: Validate Program Brackets

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import scala.collection.mutable

object Solution extends App // Initialize hash map with mappings. This simply makes the code easier to read.
{
  var mappings = new mutable.HashMap[Char, Char]
  this.mappings.put(')', '(')
  this.mappings.put('}', '{')
  this.mappings.put(']', '[')

  var reversedMappings = new mutable.HashMap[Char, Char]
  this.reversedMappings.put('(', ')')
  this.reversedMappings.put('{', '}')
  this.reversedMappings.put('[', ']')
  // Hash table that takes care of the mappings.


  def isValid(s: String): Boolean = { // Initialize a stack to be used in the algorithm.
    val stack = new mutable.Stack[Char]()
    for (i <- 0 until s.length) {
      val c = s.charAt(i)
      // If the current character is a closing bracket.
      if (mappings.contains(c)) { // Get the top element of the stack. If the stack is empty, set a dummy value of '#'
        var topElement:Char = '0'
        if (stack.isEmpty)
          topElement = '#'
        else topElement = stack.pop
        // If the mapping for this bracket doesn't match the stack's top element, return false.
        if (topElement != mappings(c))
          return false
      }
      else if(reversedMappings.contains(c)) { // If it was an opening bracket, push to the stack.
        stack.push(c)
      }
    }
    // If the stack still contains elements, then it is an invalid expression.
    stack.isEmpty
  }


  val string = "let output = function () { console.log('Anonymous function'); };"
  println(isValid(string))
}

Popularity 1/10 Helpfulness 1/10 Language scala

Source: Grepper

Tags: brackets scala

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Contributed on Sep 06 2023

Sumit Rawal

0 Answers Avg Quality 2/10

Feature #9: Validate Program Brackets

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