189. Rotate Array | Using Cyclic Replacements | Top Interview 150 | LEETCODE

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Sure, let's first convert the provided Java code to JavaScript, and then I'll explain each step.

### Explanation of Each Step

1. **Optimizing `k` (Line 7):**
- ensures that the number of rotations, `k`, is within the bounds of the array's length. This avoids unnecessary full-circle rotations.

2. **Initialization (Lines 8-10):**
- initializes a counter to track how many elements have been moved.
- The `for` loop iterates over the array. The loop starts from each index in turn (`start`), but only continues while the total number of moved elements (`count`) is less than the length of the array.

3. **Rotation Logic (Lines 11-20):**
- The `do-while` loop inside the `for` loop is where the actual rotation happens:
- current` and prev initialize the `current` position and store the value at the `start` position.
- Inside the `do-while` loop:
- calculates the new position (`next`) for the `prev` element. The modulo operation ensures the index remains within the array bounds.
- `const temp = nums[next];` temporarily stores the value at the `next` position.
- `nums[next] = prev;` places the `prev` value into its new position.
- `prev = temp;` updates `prev` to the value that was just replaced, for use in the next iteration.
- `current = next;` updates the current position to the next position.
- `count++;` increments the counter of moved elements.
- The loop continues (`while (start !== current)`) until it wraps back to the starting index, meaning that one cycle of rotation for a group of elements is complete.

4. **Cycle Completion:**
- The rotation process is complete when every element has been moved to its new position

5. **Result:**
- Upon completion, each element in the array `nums` has been rotated `k` positions to the right. The algorithm ensures that this is done efficiently and in place, without needing extra space proportional to the size of `nums`.