Walking Robot Simulation Python Solution

lcpy gen -n 874   # by problem number
lcpy gen -s walking_robot_simulation   # by problem name

Input: commands = [4,-1,3], obstacles = []
Output: 25
Explanation: The robot starts at (0, 0):
1. Move north 4 units to (0, 4).
2. Turn right to face east.
3. Move east 3 units to (3, 4).
The furthest point the robot ever gets from the origin is (3, 4), which squared is 3^2 + 4^2 = 25 units away.

Input: commands = [4,-1,4,-2,4], obstacles = [[2,4]]
Output: 65
Explanation: The robot is being tracked:
1. Move north 4 units to (0, 4).
2. Turn right to face east.
3. Move east 1 unit and get blocked by the obstacle at (2, 4), robot is at (1, 4).
4. Turn left to face north.
5. Move north 4 units to (1, 8).
The furthest point the robot ever gets from the origin is (1, 8), which squared is 1^2 + 8^2 = 65 units away.

Input: commands = [6,-1,-1,6], obstacles = []
Output: 36
Explanation: The robot starts at (0, 0):
1. Move north 6 units to (0, 6).
2. Turn right to face east.
3. Turn right to face south.
4. Move south 6 units to (0, 0).
The furthest point the robot ever gets from the origin is (0, 6), which squared is 6^2 = 36 units away.

class Solution:
    # Time: O(c + o)
    # Space: O(o)
    def robot_sim(self, commands: list[int], obstacles: list[list[int]]) -> int:
        blocked = {(x, y) for x, y in obstacles}
        x, y, dx, dy = 0, 0, 0, 1
        best = 0
        for command in commands:
            if command == -2:
                dx, dy = -dy, dx
            elif command == -1:
                dx, dy = dy, -dx
            else:
                for _ in range(command):
                    next_x, next_y = x + dx, y + dy
                    if (next_x, next_y) in blocked:
                        break
                    x, y = next_x, next_y
                best = max(best, x * x + y * y)
        return best