g0801_0900.s0818_race_car

Class Solution

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 and Description
Solution()

Method Summary

Modifier and Type	Method and 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)