Good morning! Here's our prompt for today.

You're given an array of strings containing alphabetical characters and certain $ characters. A $ represents a DELETE action whereby the character before it is deleted.

Each of these strings will be run through a method to operate on the $ DELETE action. We want to find out if the final string is the same for all of them. Let's take an example:

1let input = ["f$st", "st"];
2isDollarDeleteEqual(input);
3// true
4// true because both become "st"

Can you find a solution in O(n) time and constant space?

Constraints

• The input arrays can be of any size
• Every string has at least a single character
• The string will consist of dollar signs and lowercase alphabets
• Expected overall time complexity : O(n)
• Expected space complexity : O(n) for good solution, O(1) for asymptotically optimal solution

Try to solve this here or in Interactive Mode.

How do I practice this challenge?

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var assert = require('assert');

​

function isDollarDeleteEqual(arr) {

  // Fill in this method

  return arr;

}

​

function getFinalStr(str) {

  // Fill in this method

  return str;

}

​

// const input = ["f$st", "st"];

// console.log(isDollarDeleteEqual(input));

​

try {

  assert.equal(isDollarDeleteEqual(['f$ec', 'ec']), true);

​

  console.log('PASSED: ' + "`['f$ec', 'ec']` should return `true`");

} catch (err) {

  console.log(err);

}

​

try {

  assert.equal(isDollarDeleteEqual(['a90$n$c$se', 'a90n$cse']), false);

​

  console.log(

    'PASSED: ' + "`['a90$n$c$se', 'a90n$cse']` should return `false`"

  );

Here's our guided, illustrated walk-through.

How do I use this guide?