Given a road having n cars arranged from left to right at unique positions. Each car has a predefined movement direction or remains stationary, represented by a string directions of length n. In the string, 'L' denotes a car moving left, 'R' denotes a car moving right, and 'S' denotes a stationary car. All moving cars travel at the same speed. When two cars moving in opposite directions collide, the collision count increases by 2, and when a moving car collides with a stationary car, the collision count increases by 1. After any collision, the cars involved stop and remain stationary at the point of collision.
Your task is to calculate the total number of collisions that occur on the road.
Input: directions = "RLLRS"
Output: 4
Explanation:
Car 1 ('R') collides with Car 2 ('L'), Total Collisons: 0+2=2
Car 2, now stationary, collides with Car 3 ('L'), Total Collisons: 2+1=3
Car 4 ('R') collides with Car 5 ('S'), Total Collisons: 3+1=4.
Input: directions = "SSRRLL"
Output: 4
Explanation:
Car 4 ('R') collides with Car 5 ('L'),Total Collisons: 0+2=2.
Car 5 ('L') collides with Car 5 after it becomes stationary,Total Collisons: 2+1=3.
Car 3 ('L') collides with Car 4 after it becomes stationary,Total Collisons: 3+1=4.
Input: directions = "RRSSLLL"