Software Engineer

A wiggle sequence is a sequence where the differences between successive numbers strictly alternate between positive and negative. The first difference (if one exists) may be either positive or negative. A sequence with one element, or two non-equal elements, is trivially a wiggle sequence.

For example:

• [1, 7, 4, 9, 2, 5] is a wiggle sequence because the differences (6, -3, 5, -7, 3) alternate between positive and negative.
• [1, 4, 7, 2, 5] is not a wiggle sequence because its first two differences are positive.
• [1, 7, 4, 5, 5] is not a wiggle sequence because the last difference is zero.

A subsequence is obtained by deleting some elements (possibly zero) from the original sequence, keeping the remaining elements in their original order.

Given an integer array nums, return the length of the longest wiggle subsequence of nums.

There are n cars on an infinitely long road, numbered from 0 to n - 1 from left to right, with each car at a unique position. You are given a 0-indexed string directions of length n, where:

• directions[i] = 'L' → the ith car moves left
• directions[i] = 'R' → the ith car moves right
• directions[i] = 'S' → the ith car stays stationary

All moving cars travel at the same speed. Collisions are calculated as follows:

1. When two cars moving in opposite directions collide, the collision count increases by 2.
2. When a moving car collides with a stationary car, the collision count increases by 1.
3. After a collision, the cars involved stop at the collision point and cannot move further. Cars cannot change their direction otherwise.

Return the total number of collisions that will occur on the road.