```
public class Solution
extends Object
```
818 - Race Car\. Hard Your car starts at position `0` and speed `+1` on an infinite number line. Your car can go into negative positions. Your car drives automatically according to a sequence of instructions `'A'` (accelerate) and `'R'` (reverse): * When you get an instruction `'A'`, your car does the following: * `position += speed` * `speed *= 2` * When you get an instruction `'R'`, your car does the following: * If your speed is positive then `speed = -1` * otherwise `speed = 1`Your position stays the same. For example, after commands `"AAR"`, your car goes to positions `0 --> 1 --> 3 --> 3`, and your speed goes to `1 --> 2 --> 4 --> -1`. Given a target position `target`, return _the length of the shortest sequence of instructions to get there_. **Example 1:** **Input:** target = 3 **Output:** 2 **Explanation:** The shortest instruction sequence is "AA". Your position goes from 0 --> 1 --> 3. **Example 2:** **Input:** target = 6 **Output:** 5 **Explanation:** The shortest instruction sequence is "AAARA". Your position goes from 0 --> 1 --> 3 --> 7 --> 7 --> 6. **Constraints:** * 1 <= target <= 10⁴

Class Solution