Count players reaching end with moving watchers

You are given a 1D line of L cells indexed 0..L-1. The end cell is L-1.

There are:

• W watchers with initial integer positions watchers[] .
• P players with initial integer positions players[] .
• A time horizon T (non-negative integer, number of unit-time steps).
• An unsorted list flipTimes[] of integer timestamps. At each timestamp t in flipTimes, all watchers reverse direction .

Movement model (discrete time):

• Time steps are t = 0, 1, ..., T-1 .
• Each watcher has a facing direction ( LEFT or RIGHT ). All watchers start facing LEFT at time 0 .
• At the start of each step t , if t is in flipTimes , all watchers reverse direction.
• Watching rule: At step t , a watcher at position x :
  • if facing LEFT , watches all cells < x ;
  • if facing RIGHT , watches all cells > x . A player is considered watched if at least one watcher watches the player’s current cell.
• Player move: During step t , each player tries to move one cell to the right (from p to min(p+1, L-1) ), but if the player is watched at the start of the step, the player cannot move and stays in place .
• Watcher move: After all players have (attempted) to move, each watcher moves one cell in its facing direction:
  • LEFT : x = max(x-1, 0)
  • RIGHT : x = min(x+1, L-1)

Task:

• After performing exactly T steps, return how many players are at cell L-1 .

Notes / clarifications:

• Multiple players and watchers may occupy the same cell.
• flipTimes[] may contain duplicates and is not sorted.

Write a function that takes (L, watchers, players, T, flipTimes) and returns the count.

Suggested constraints (for implementation):

• 1 <= L <= 2e5
• 0 <= W, P <= 2e5
• 0 <= T <= 2e5
• 0 <= flipTimes[i] <= T-1