Challenge #13: 🤖 Is the robot back?

The elves at the North Pole have created a special robot 🤖 that helps Santa Claus distribute gifts inside a large warehouse. The robot moves on a 2D plane and we start from the origin (0, 0).

We want to know if, after executing a series of movements, the robot returns to exactly where it started.

The robot's basic commands are:

• L: Move to the left
• R: Move to the right
• U: Move upwards
• D: Move downwards

But it also has certain modifiers for the movements:

• *: The movement is done with double intensity (e.g., *R means RR)
• !: The next movement is inverted (e.g., R!L is considered as RR)
• ?: The next movement is done only if it hasn't been done before (e.g., R?R means R)

Note: When the movement is inverted with ! the inverted movement is counted and not the original one. For example, !U?U inverts the U movement, so it counts as having done the D movement but not the U. Thus, !U?U translates to D?U, and therefore, the final U movement is done.

You must return:

• true: if the robot returns exactly to where it started
• [x, y]: if the robot does not return to where it started, return the position where it stopped

isRobotBack('R')     // [1, 0]
isRobotBack('RL')    // true
isRobotBack('RLUD')  // true
isRobotBack('*RU')   // [2, 1]
isRobotBack('R*U')   // [1, 2]
isRobotBack('LLL!R') // [-4, 0]
isRobotBack('R?R')   // [1, 0]
isRobotBack('U?D')   // true
isRobotBack('R!L')   // [2,0]
isRobotBack('U!D')   // [0,2]
isRobotBack('R?L')   // true
isRobotBack('U?U')   // [0,1]
isRobotBack('*U?U')  // [0,2]
isRobotBack('U?D?U') // true

// Step-by-step examples:
isRobotBack('R!U?U') // [1,0]
// 'R'  -> moves to the right 
// '!U' -> inverts and becomes 'D'
// '?U' -> moves upwards, because the 'U' movement hasn't been done yet

isRobotBack('UU!U?D') // [0,1]
// 'U'  -> moves upwards
// 'U'  -> moves upwards
// '!U' -> inverts and becomes 'D'
// '?D' -> does not move, since the 'D' movement has already been done