AoC 2019 D11: Space Police

C++ | Problem statement | Source code | Tags: IntcodeManual inspection

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The only additional capability from day 7 is that instead of having one number output at a time, the program now produces two outputs before pausing. Since the size is fixed, I just call run_until_output() twice to get both outputs.

Both parts work the same way. I keep track of the robot's position and direction, and a map of painted panels. Each time, I use send_input() to provide the current panel color, then call run_until_output() to get the new color and direction. Abstractly:

int x = 0, y = 0;
int dir_x = 0, dir_y = -1;
while (!prog.halted) {
    prog.send_input(panels.find({x, y}) != panels.end() ? panels[{x, y}] : 0);
    prog.run_until_output();
    if (prog.halted) break;
    panels[{x, y}] = prog.pop_output();
    prog.run_until_output();
    int turn = prog.pop_output();
    // Update direction
}
cpp

Again, I take a second to admire the ASCII art in part 2:

 ###   ##  #  # ###  #    ###  #  # #  #
 #  # #  # # #  #  # #    #  # #  # # #
 #  # #    ##   #  # #    #  # #  # ##
 ###  #    # #  ###  #    ###  #  # # #
 #    #  # # #  # #  #    #    #  # # #
 #     ##  #  # #  # #### #     ##  #  #

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