4kyu_ValidBraces.js

// 4kyu - Valid Braces

// Description:

// Write a function called validBraces that takes a string of braces, and determines if 
// the order of the braces is valid. validBraces should return true if the string is 
// valid, and false if it's invalid.

// This Kata is similar to the Valid Parentheses Kata, but introduces four new characters. 
// Open and closed brackets, and open and closed curly braces. Thanks to @arnedag for the 
// idea!

// All input strings will be nonempty, and will only consist of open parentheses '(' , 
// 	closed parentheses ')', open brackets '[', closed brackets ']', open curly braces 
// '{' and closed curly braces '}'.

// What is considered Valid? A string of braces is considered valid if all braces are 
// matched with the correct brace. 
// For example:
// '(){}[]' and '([{}])' would be considered valid, while '(}', '[(])', and '[({})](]' 
// would be considered invalid.

// Examples: 
// validBraces( "(){}[]" ) => returns true 
// validBraces( "(}" ) => returns false 
// validBraces( "[(])" ) => returns false 
// validBraces( "([{}])" ) => returns true 

function validBraces(braces){
  var arr = [];
  
  for(var i = 0; i < braces.length; i++) {
      if(braces[i] === "{") {
          arr.unshift("}");
      } else if (braces[i] === "[") {
          arr.unshift("]");
      } else if (braces[i] === "(") {
          arr.unshift(")");
      } else if (braces[i] !== arr[0]){
          return false;
      } else {
          arr.shift();
      }
  }
  return arr.length === 0;
}