Twin Strings. Two strings, a and b, are said to be twins only if they can be made equivalent by performing some number of operations on one or both strings...

Twins.js

function Twins(a, b) {
    var result = Array(a.length),
    swap = function(arr, index) {
      var tmp = arr[index];
      arr[index] = arr[index + 2];
      arr[index + 2] = tmp;
      return arr;
		},
    swapBack = function(str, index) {
    	var arr = str.split('');
      return swap(arr, index).join('');
    };

    for (var i = 0; i < a.length; i++) {
				// No need to compare
        if (!b[i]) {
					break;
        }
        // Already equal
        else if (a[i] === b[i]) {
		   			result[i] = "Yes";
           continue;
        }

        var verification = [];
        verification.push(a[i]);

        for (var z = 0; z < verification.length; z++) {
        	var str = verification[z],
          		txtArr = str.split('');
              
					console.log('iter', str);

          for (var j = 0; j < txtArr.length; j++) {
              // No pair
              if (!txtArr[j+2]) {
                  break;
              }

              // Swap
          		console.log('inside iter', txtArr[j], txtArr[j+2]);
              swap(txtArr, j);

              // Compare each time
              var check = txtArr.join('');
              if (check === b[i]) {
                result[i] = "Yes";
                console.log('YES');
                break;
              }
              else {
              	var checkBack = swapBack(check, j);
              	if (verification.indexOf(check) === -1) {
                	verification.push(check);
                }
              	if (verification.indexOf(checkBack) === -1) {
                	verification.push(checkBack);
                 }
              }
          };
          
          if (result[i] === "Yes") {
          	break;
          }
        };

				console.log('verification', verification);
        !result[i] && (result[i] = "No");
    }

  return result;
}

console.log(Twins(["ddccdab", "dcba"], ["ddcabcd", "abcd"]));

Hi @SergeyNarozhnyy,

I have built a logic in PHP language, that can accept n number of indexes in the passed array. I am handling validations i.e. If both arrays have the different number of indexes. And if any index in the array has different length string/data.

https://gist.github.com/tanmay27vats/5727b3e37cda65a68e87abfdb3f8f9a7