Optimize Insertion Sort

[AryanAhadinia]

No description provided.

[JackyYin]

I don't get the advantage of this change.
You can swap the elements when compare the elements, why go through the list again?

[AryanAhadinia]

I don't get the advantage of this change.
You can swap the elements when compare the elements, why go through the list again?

Consider we want to insert 5-th element (value = 2) in correct place in this list:
1, 3, 4, 5, 6, 2, 8, 9, 7 --> 1, 2, 3, 4, 5, 6, 8, 9, 7

In pervious algorithm, we had to swap 4 times, (6, 2) and (5, 2) and (4, 2) and (3, 2). Since each swap needs assignment 2 times as least, we'll have variable assignment 8 times in minimum. In general, if we need swaps k times, we'll have 2 * k assignments.

But in new algorithm in same condition, we shift 3, 4, 5 and 6 then insert 2 in correct index. then we'll have k + 2 assignments which is better than 2 * k

[JackyYin]

I don't get the advantage of this change.
You can swap the elements when compare the elements, why go through the list again?

Consider we want to insert 5-th element (value = 2) in correct place in this list:
1, 3, 4, 5, 6, 2, 8, 9, 7 --> 1, 2, 3, 4, 5, 6, 8, 9, 7

In pervious algorithm, we had to swap 4 times, (6, 2) and (5, 2) and (4, 2) and (3, 2). Since each swap needs assignment 2 times as least, we'll have variable assignment 8 times in minimum. In general, if we need swaps k times, we'll have 2 * k assignments.

But in new algorithm in same condition, we shift 3, 4, 5 and 6 then insert 2 in correct index. then we'll have k + 2 assignments which is better than 2 * k

@AryanAhadinia Thanks for your explaination.
How about this version to avoid the 2 * k assignments also avoid going through the k elements again?

  sort(originalArray) {
    const array = [...originalArray];

    // Go through all array elements...
    for (let i = 0; i < array.length; i += 1) {
      let currentIndex = i;
      let tmp = array[i];

      // Call visiting callback.
      this.callbacks.visitingCallback(array[i]);

      // Go and check if previous elements and greater then current one.
      // If this is the case then swap that elements.
      while (
        currentIndex > 0
        && this.comparator.lessThan(array[currentIndex], array[currentIndex - 1])
      ) {
        // Call visiting callback.
        this.callbacks.visitingCallback(array[currentIndex - 1]);

        // Swap the elements.
        array[currentIndex] = array[currentIndex - 1];

        // Shift current index left.
        currentIndex -= 1;
      }

      array[currentIndex] = tmp;
    }

    return array;
  }

[AryanAhadinia]

Yes, it is correct I think, I'll work on this and I'll commit changes ASAP.

[AryanAhadinia]

I don't get the advantage of this change.
You can swap the elements when compare the elements, why go through the list again?

Consider we want to insert 5-th element (value = 2) in correct place in this list:
1, 3, 4, 5, 6, 2, 8, 9, 7 --> 1, 2, 3, 4, 5, 6, 8, 9, 7
In pervious algorithm, we had to swap 4 times, (6, 2) and (5, 2) and (4, 2) and (3, 2). Since each swap needs assignment 2 times as least, we'll have variable assignment 8 times in minimum. In general, if we need swaps k times, we'll have 2 * k assignments.
But in new algorithm in same condition, we shift 3, 4, 5 and 6 then insert 2 in correct index. then we'll have k + 2 assignments which is better than 2 * k

@AryanAhadinia Thanks for your explaination.
How about this version to avoid the 2 * k assignments also avoid going through the k elements again?

  sort(originalArray) {
    const array = [...originalArray];

    // Go through all array elements...
    for (let i = 0; i < array.length; i += 1) {
      let currentIndex = i;
      let tmp = array[i];

      // Call visiting callback.
      this.callbacks.visitingCallback(array[i]);

      // Go and check if previous elements and greater then current one.
      // If this is the case then swap that elements.
      while (
        currentIndex > 0
        && this.comparator.lessThan(array[currentIndex], array[currentIndex - 1])
      ) {
        // Call visiting callback.
        this.callbacks.visitingCallback(array[currentIndex - 1]);

        // Swap the elements.
        array[currentIndex] = array[currentIndex - 1];

        // Shift current index left.
        currentIndex -= 1;
      }

      array[currentIndex] = tmp;
    }

    return array;
  }

Actually, there is a little mistake in this code, I'll correct this and commit in few seconds.

[AryanAhadinia]

Now it is optimized!