1function reverseString(string) {
2  let strArray = string.split("");
3  let start = 0;
4  let end = strArray.length - 1;
5  let temp = "";
6  while (start < end) {
7    temp = strArray[end];
8    strArray[end] = strArray[start];
9    strArray[start] = temp;
10    start++;
11    end--;
12  }
13  return strArray.join("");
14}
15
16function isStringPalindrome(string) {
17  return string === reverseString(string);
18}
19let element = [];
20function stringSubsequence(input, output) {
21  if (input.length === 0) {
22    isStringPalindrome(output) && element.push(output);
23    return;
24  }
25  stringSubsequence(input.substring(1), output);
26  stringSubsequence(input.substring(1), output + input[0]);
27}
28
29const inputString = "abc";
30const inputString1 = "abcd";
31const inputString2 = "aab";
32// stringSubsequence(inputString, "");
33// stringSubsequence(inputString1, "");
34stringSubsequence(inputString2, "");
35console.log(element.length - 1);
36