removeDuplicates func complexity analysis + refactoring for better efficiency

Author: Mikiyas-STP

Sprint-1/JavaScript/removeDuplicates/removeDuplicates.mjs

@@ -8,29 +8,43 @@
  * @param {Array} inputSequence - Sequence to remove duplicates from
  * @returns {Array} New sequence with duplicates removed
  */
-export function removeDuplicates(inputSequence) {
-  const uniqueItems = [];
+// export function removeDuplicates(inputSequence) {
+//   const uniqueItems = [];
+
+//   for (
+//     let currentIndex = 0;
+//     currentIndex < inputSequence.length;
+//     currentIndex++
+//   ) {
+//     let isDuplicate = false;
+//     for (
+//       let compareIndex = 0;
+//       compareIndex < uniqueItems.length;
+//       compareIndex++
+//     ) {
+//       if (inputSequence[currentIndex] === uniqueItems[compareIndex]) {
+//         isDuplicate = true;
+//         break;
+//       }
+//     }
+//     if (!isDuplicate) {
+//       uniqueItems.push(inputSequence[currentIndex]);
+//     }
+//   }
+
+//   return uniqueItems;
+// }
 
-  for (
-    let currentIndex = 0;
-    currentIndex < inputSequence.length;
-    currentIndex++
-  ) {
-    let isDuplicate = false;
-    for (
-      let compareIndex = 0;
-      compareIndex < uniqueItems.length;
-      compareIndex++
-    ) {
-      if (inputSequence[currentIndex] === uniqueItems[compareIndex]) {
-        isDuplicate = true;
-        break;
-      }
-    }
-    if (!isDuplicate) {
-      uniqueItems.push(inputSequence[currentIndex]);
-    }
-  }
 
-  return uniqueItems;
+// My Analysis Result
+// Time Complexity- It has a nested loop structure, giving it a growth of O(n * n) = O(n²). quadratic growth.
+// Space Complexity- A new array 'uniqueItems' is created which can grow up to the size of the input, making the space complexity O(n).
+// The inefficiency of this program is due to the nested loop: 
+// for every item, it slowly rescans the results to check for duplicates.
+
+//refactored code
+export function removeDuplicates(inputSequence) {
+  return [...new Set(inputSequence)];
 }
+// Here the time complexity is reduced to an optimal level O(n).
+// For the space complexity, I have O(n) as well because the new Set can store up to n unique items.