Program to check if two stacks are equal

An algorithm to check if two stacks are equal in javascript.

Example

Input:
2 9 3 7 5
2 9 3 7 5

Output:
true

Implementation

• First we will check if the length of both the stacks are same, if they are not equal then return false.
• If the length are same, then check each element in both the stacks by peeking the elements.
• If they are equal then pop the elements else return false.
• At the end if all elements are same in both the stack then return true.

let equalStacks = (stack1, stack2) => {
  //If length is not equal
  //Then return false
  if(stack1.size() !== stack2.size()){
    return false;
  }
  
  //Check if each element in both the stack are equal
  while(!stack1.isEmpty()){
    if(stack1.peek() === stack2.peek()){
      stack1.pop();
      stack2.pop();
    }else{
      return false;
    }
  }
  
  return true;
}

Input:
let stack1 = new stackUsingLL();
stack1.push(2);
stack1.push(9);
stack1.push(3);
stack1.push(7);
stack1.push(5);

let stack2 = new stackUsingLL();
stack2.push(2);
stack2.push(9);
stack2.push(3);
stack2.push(7);
stack2.push(5);

console.log(equalStacks(stack1, stack2));

Output:
true

Time complexity: O(n).
Space complexity: O(1).

Time and Space complexity

• We are checking each element in both the stack, so Time complexity is O(n).
• We are using constant space, so Space complexity is O(1).