Use Stack to check if String is balanced - Node.js Data Structure

Node.js examples for Data Structure:Stack

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Description

Use Stack to check if String is balanced

Demo Code



function Stack(){
  this.top = -1;//from   ww w  .j a  va2s . c o m
  this.arr = [];
}

Stack.prototype.push = function(val){
  this.arr.push(val);
  this.top += 1;
}

Stack.prototype.pop = function(val){
  if (this.top == -1) {
    throw "Stack is empty";
  }
  this.top -= 1;
  return this.arr.pop();
}

Stack.prototype.isEmpty = function(){
  return this.arr.length == 0;
}

Stack.prototype.peek = function(){
  if (this.top == -1) {
    throw "Stack is empty";
  }
  return this.arr[this.arr.length - 1];
}

function isStringbalanced(testString){
  myStack = new Stack();
  var isBalanced = true;

  for (var i in testString) {
    if (testString[i] == "("){
      myStack.push("(");
    } else if (testString[i] == ")") {
        if (myStack.isEmpty()) {
           isBalanced = false;
        } else {
          elem = myStack.pop()
          if (elem != "("){
            isBalanced = false;
          }
        }
    }
  }

  if (!myStack.isEmpty()){
    isBalanced = false
  }
  return isBalanced
}

testString1 = "()((a+b)-c)";
testString2 = "()()())";



console.log(isStringbalanced(testString1)?"Balanced":"Not Balanced");
console.log(isStringbalanced(testString2)?"Balanced":"Not Balanced");

myStack = new Stack()
myStack.push(2)
myStack.push(12)
myStack.push(76)
console.log(myStack.peek())
myStack.pop()
console.log(myStack.peek())
myStack.pop()
myStack.pop()
myStack.peek()

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