Super Reduced String

This one was a pain in the ass. I could get all of the test cases except for the last one, which I still don’t totally understand why I didn’t get. But I did get a hint to try recursion, which I did and it worked.

Steve has a string of lowercase characters in range ascii[[“a”..“z”]]. He wants to reduce the string to its shortest length by doing a series of operations. In each operation, he selects a pair of adjacent lowercase letters that match, and he deletes them. For instance, the string aab could be shortened to b in one operation.

Steve’s task is to delete as many characters as possible using this method and print the resulting string. If the final string is empty, return “Empty String”. Case

superReducedString(“aaabccddd”) ➞ “abd”

Explanation:

“aaabccddd” -> “abccddd” -> “abddd” -> “abd”

Examples

superReducedString(“cccxllyyy”) ➞ “cxy”

superReducedString(“aa”) ➞ “Empty String”

superReducedString(“baab”) ➞ “Empty String”

superReducedString(“fghiiijkllmnnno”) ➞ “fghijkmno”

superReducedString(“chklssstt”) ➞ “chkls”

My solution

const superReducedString = str => 
  str.match(/(.)\1/gm) ? superReducedString(str.replace(/(.)\1/gm, ''))  : str ? str : 'Empty String' 
   


superReducedString("cccxllyyy") // "cxy"
superReducedString("aa") // "Empty String"
superReducedString("baab") // "Empty String"
superReducedString("fghiiijkllmnnno") // "fghijkmno"
superReducedString("chklssstt") // "chkls"
superReducedString("acdqglrfkqyuqfjkxyqvnrtysfrzrmzlygfveulqfpdbhlqdqrrqdqlhbdpfqluevfgylzmrzrfsytrnvqyxkjfquyqkfrlacdqj") //"acdqgacdqj"

Other solutions

Super simple and terse, note that regex is defined outside of the function superReducedString

const r = /(.)\1/g;
const superReducedString = s => r.test(s) ? superReducedString(s.replace(r, "")) : s || "Empty String";
//cvf

This solution uses a for loop, which I initially tried but couldn’t get to work fully.

function superReducedString(str) {
 let output = str.split("");
 for(let i = 0; i < output.length; i++){
   if(output[i] === output[i+1]){
     output.splice(i, 2);
     i = -1;
    }
  }
 return output.length === 0 ? "Empty String" : output.join("");
}
//czaplitto