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Backspace String Compare

Problem statement​

Given two strings s and t, return true if they are equal when both are typed into empty text editors. '#' means a backspace character.

Note that after backspacing an empty text, the text will continue empty.

Example 1:

Input: s = "ab#c", t = "ad#c"Output: trueExplanation: Both s and t become "ac".

Example 2:

Input: s = "ab##", t = "c#d#"Output: trueExplanation: Both s and t become "".

Example 3:

Input: s = "a#c", t = "b"Output: falseExplanation: s becomes "c" while t becomes "b".

Constraints:

  • 1 <= s.length, t.length <= 200
  • s and t only contain lowercase letters and '#' characters.

Follow up: Can you solve it in O(n) time and O(1) space?

My solution​

/**
 * @param {string} s
 * @param {string} t
 * @return {boolean}
 */
var backspaceCompare = function(s, t) {
    return returnString(s) === returnString(t)
};

function returnString(s) {
    const stack = [];
    
    for (const char of s.split("")) {
        if (char === "#") {
            stack.pop();
        } else {
            stack.push(char)
        }
    }
    
    return stack.join("")
}