Solution (leetcode-in-java 1.20 API)

java.lang.Object
- g0801_0900.s0818_race_car.Solution

```
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 = 1Your 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

- Constructor Summary
  
  Constructors
  Constructor Description
  
  Solution()
- Method Summary
  
  All Methods Instance Methods Concrete Methods
  Modifier and Type Method Description
  
  int racecar(int target)
  - Methods inherited from class java.lang.Object
    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail
- Solution
```
public Solution()
```

Method Detail
- racecar
```
public int racecar(int target)
```