2019: d17: ex2: add solution

2019/d17/ex2/ex2.py

@@ -0,0 +1,350 @@
+#!/usr/bin/env python
+
+
+import sys
+from copy import deepcopy
+from dataclasses import dataclass, field
+from enum import Enum, IntEnum, auto
+from typing import List, NamedTuple
+
+
+class ParameterMode(IntEnum):
+    POSITION = 0  # Acts on address
+    IMMEDIATE = 1  # Acts on the immediate value
+    RELATIVE = 2  # Acts on offset to relative base
+
+
+class Instruction(NamedTuple):
+    address: int  # The address of the instruction, for convenience
+    op: int  # The opcode
+    p1_mode: ParameterMode  # Which mode is the first parameter in
+    p2_mode: ParameterMode  # Which mode is the second parameter in
+    p3_mode: ParameterMode  # Which mode is the third parameter in
+
+
+def lookup_ops(index: int, memory: List[int]) -> Instruction:
+    digits = list(map(int, str(memory[index])))
+    a, b, c, d, e = [0] * (5 - len(digits)) + digits  # Pad with default values
+    return Instruction(
+        address=index,
+        op=d * 10 + e,
+        p1_mode=ParameterMode(c),
+        p2_mode=ParameterMode(b),
+        p3_mode=ParameterMode(a),
+    )
+
+
+class InputInterrupt(Exception):
+    pass
+
+
+class OutputInterrupt(Exception):
+    pass
+
+
+@dataclass
+class Computer:
+    memory: List[int]  # Memory space
+    rip: int = 0  # Instruction pointer
+    input_list: List[int] = field(default_factory=list)
+    output_list: List[int] = field(default_factory=list)
+    is_halted: bool = field(default=False, init=False)
+    relative_base: int = field(default=0, init=False)
+
+    def run(self) -> None:
+        while not self.is_halted:
+            self.run_single()
+
+    def run_no_output_interrupt(self) -> None:
+        while not self.is_halted:
+            try:
+                self.run_single()
+            except OutputInterrupt:
+                continue
+
+    def run_single(self):  # Returns True when halted
+        instr = lookup_ops(self.rip, self.memory)
+        if instr.op == 99:  # Halt
+            self.is_halted = True
+        elif instr.op == 1:  # Sum
+            self._do_addition(instr)
+        elif instr.op == 2:  # Multiplication
+            self._do_multiplication(instr)
+        elif instr.op == 3:  # Load from input
+            self._do_input(instr)
+        elif instr.op == 4:  # Store to output
+            self._do_output(instr)
+        elif instr.op == 5:  # Jump if true
+            self._do_jump_if_true(instr)
+        elif instr.op == 6:  # Jump if false
+            self._do_jump_if_false(instr)
+        elif instr.op == 7:  # Less than
+            self._do_less_than(instr)
+        elif instr.op == 8:  # Equal to
+            self._do_equal_to(instr)
+        elif instr.op == 9:  # Change relative base
+            self._do_change_relative_base(instr)
+        else:
+            assert False  # Sanity check
+
+    def _fill_to_addres(self, address: int) -> None:
+        values = address - len(self.memory) + 1
+        if values <= 0:
+            return
+        for __ in range(values):
+            self.memory.append(0)
+
+    def _get_value(self, mode: ParameterMode, val: int) -> int:
+        if mode == ParameterMode.POSITION:
+            assert 0 <= val  # Sanity check
+            self._fill_to_addres(val)
+            return self.memory[val]
+        elif mode == ParameterMode.RELATIVE:
+            val += self.relative_base
+            assert 0 <= val  # Sanity check
+            self._fill_to_addres(val)
+            return self.memory[val]
+        assert mode == ParameterMode.IMMEDIATE  # Sanity check
+        return val
+
+    def _set_value(self, mode: ParameterMode, address: int, value: int) -> None:
+        if mode == ParameterMode.RELATIVE:
+            address += self.relative_base
+        else:
+            assert mode == ParameterMode.POSITION  # Sanity check
+
+        assert address >= 0  # Sanity check
+        self._fill_to_addres(address)
+
+        self.memory[address] = value
+
+    def _do_addition(self, instr: Instruction) -> None:
+        lhs = self._get_value(instr.p1_mode, self.memory[instr.address + 1])
+        rhs = self._get_value(instr.p2_mode, self.memory[instr.address + 2])
+        dest = self.memory[instr.address + 3]
+
+        self._set_value(instr.p3_mode, dest, lhs + rhs)
+
+        self.rip += 4  # Length of the instruction
+
+    def _do_multiplication(self, instr: Instruction) -> None:
+        lhs = self._get_value(instr.p1_mode, self.memory[instr.address + 1])
+        rhs = self._get_value(instr.p2_mode, self.memory[instr.address + 2])
+        dest = self.memory[instr.address + 3]
+
+        self._set_value(instr.p3_mode, dest, lhs * rhs)
+
+        self.rip += 4  # Length of the instruction
+
+    def _do_input(self, instr: Instruction) -> None:
+        if len(self.input_list) == 0:
+            raise InputInterrupt  # No input, halt until an input is provided
+
+        value = int(self.input_list.pop(0))
+        param = self.memory[instr.address + 1]
+
+        self._set_value(instr.p1_mode, param, value)
+
+        self.rip += 2  # Length of the instruction
+
+    def _do_output(self, instr: Instruction) -> None:
+        value = self._get_value(instr.p1_mode, self.memory[instr.address + 1])
+
+        self.output_list.append(value)
+
+        self.rip += 2  # Length of the instruction
+        raise OutputInterrupt  # Alert that we got an output to give
+
+    def _do_jump_if_true(self, instr: Instruction) -> None:
+        cond = self._get_value(instr.p1_mode, self.memory[instr.address + 1])
+        value = self._get_value(instr.p2_mode, self.memory[instr.address + 2])
+
+        if cond != 0:
+            self.rip = value
+        else:
+            self.rip += 3  # Length of the instruction
+
+    def _do_jump_if_false(self, instr: Instruction) -> None:
+        cond = self._get_value(instr.p1_mode, self.memory[instr.address + 1])
+        value = self._get_value(instr.p2_mode, self.memory[instr.address + 2])
+
+        if cond == 0:
+            self.rip = value
+        else:
+            self.rip += 3  # Length of the instruction
+
+    def _do_less_than(self, instr: Instruction) -> None:
+        lhs = self._get_value(instr.p1_mode, self.memory[instr.address + 1])
+        rhs = self._get_value(instr.p2_mode, self.memory[instr.address + 2])
+        dest = self.memory[instr.address + 3]
+
+        self._set_value(instr.p3_mode, dest, 1 if lhs < rhs else 0)
+
+        self.rip += 4  # Length of the instruction
+
+    def _do_equal_to(self, instr: Instruction) -> None:
+        lhs = self._get_value(instr.p1_mode, self.memory[instr.address + 1])
+        rhs = self._get_value(instr.p2_mode, self.memory[instr.address + 2])
+        dest = self.memory[instr.address + 3]
+
+        self._set_value(instr.p3_mode, dest, 1 if lhs == rhs else 0)
+
+        self.rip += 4  # Length of the instruction
+
+    def _do_change_relative_base(self, instr: Instruction) -> None:
+        value = self._get_value(instr.p1_mode, self.memory[instr.address + 1])
+
+        self.relative_base += value
+        self.rip += 2  # Length of the instruction
+
+
+class Position(NamedTuple):
+    x: int
+    y: int
+
+
+class Direction(Enum):
+    NORTH = auto()
+    WEST = auto()
+    SOUTH = auto()
+    EAST = auto()
+
+
+DIRECTIONS = [d for d in Direction]
+ARROW_DIRECTION = {
+    "^": Direction.NORTH,
+    "v": Direction.SOUTH,
+    "<": Direction.WEST,
+    ">": Direction.EAST,
+}
+DIRECTION_OFFSET = {
+    Direction.NORTH: (-1, 0),
+    Direction.SOUTH: (1, 0),
+    Direction.WEST: (0, -1),
+    Direction.EAST: (0, 1),
+}
+
+
+def turn(d: Direction, turn: str) -> Direction:
+    def turn_left() -> Direction:
+        return DIRECTIONS[(DIRECTIONS.index(d) + 1) % len(DIRECTIONS)]
+
+    def turn_right() -> Direction:
+        return DIRECTIONS[DIRECTIONS.index(d) - 1]
+
+    if turn == "L":
+        return turn_left()
+    elif turn == "R":
+        return turn_right()
+    assert False  # Sanity check
+
+
+def find_arrow(mapped_view: List[List[str]]) -> Position:
+    for x in range(len(mapped_view)):
+        for y in range(len(mapped_view[0])):
+            if mapped_view[x][y] in ARROW_DIRECTION:
+                return Position(x, y)
+
+    assert False  # Sanity check
+
+
+def get_path(mapped_view: List[List[str]]) -> List[str]:
+    pos = find_arrow(mapped_view)
+
+    def pos_is_valid(p: Position) -> bool:
+        return 0 <= p.x < len(mapped_view) and 0 <= p.y < len(mapped_view[0])
+
+    def pos_is_scaffold(p: Position) -> bool:
+        return pos_is_valid(p) and mapped_view[p.x][p.y] != "."
+
+    direction = ARROW_DIRECTION[mapped_view[pos.x][pos.y]]
+    ans: List[str] = []
+
+    def advance_until_stopped(turn_string: str) -> bool:
+        nonlocal pos
+        nonlocal direction
+        d = turn(direction, turn_string)
+        offset = DIRECTION_OFFSET[d]
+        neighbor = Position(*(a + b for a, b in zip(pos, offset)))
+        tot = 0
+        while pos_is_scaffold(neighbor):
+            tot += 1
+            mapped_view[pos.x][pos.y] = "@"
+            pos = neighbor
+            neighbor = Position(*(a + b for a, b in zip(pos, offset)))
+
+        if tot == 0:
+            return False
+        direction = d
+        ans.append(turn_string)
+        ans.append(str(tot))
+        return True
+
+    has_no_neighbors = False
+    while not has_no_neighbors:
+        for turn_string in ("L", "R"):
+            if advance_until_stopped(turn_string):
+                break
+        else:
+            has_no_neighbors = True
+    return ans
+
+
+def sequitur_algorithm(path: str) -> None:
+    # FIXME: seems like a good candidate for compression
+    pass
+
+
+def main() -> None:
+    memory = [int(n) for n in sys.stdin.read().split(",")]
+    camera = Computer(deepcopy(memory))
+
+    camera.run_no_output_interrupt()
+
+    view = "".join(chr(c) for c in camera.output_list)
+    mapped_view = [[c for c in line] for line in view.split("\n") if line != ""]
+
+    path = get_path(mapped_view)
+    print(path)
+
+    # I didn't want to write the compression algorithm when I could just use Vim
+    # The answere is A,B,B,A,C,A,A,C,B,C
+    # A: R,8,L,12,R,8
+    # B: R,12,L,8,R,10
+    # C: R,8,L,8,L,8,R,8,R,10
+
+    ans = "A,B,B,A,C,A,A,C,B,C"
+    A = "R,8,L,12,R,8"
+    B = "R,12,L,8,R,10"
+    C = "R,8,L,8,L,8,R,8,R,10"
+
+    assert len(ans) <= 20  # Sanity check
+    assert len(A) <= 20  # Sanity check
+    assert len(B) <= 20  # Sanity check
+    assert len(C) <= 20  # Sanity check
+
+    memory[0] = 2  # Wake up the robot
+    robot = Computer(memory)
+
+    for c in ans:
+        robot.input_list.append(ord(c))
+    robot.input_list.append(ord("\n"))
+    for c in A:
+        robot.input_list.append(ord(c))
+    robot.input_list.append(ord("\n"))
+    for c in B:
+        robot.input_list.append(ord(c))
+    robot.input_list.append(ord("\n"))
+    for c in C:
+        robot.input_list.append(ord(c))
+    robot.input_list.append(ord("\n"))
+
+    for c in "n\n":  # Do not output the video feed
+        robot.input_list.append(ord(c))
+
+    robot.run_no_output_interrupt()
+    print(robot.output_list.pop())
+
+
+if __name__ == "__main__":
+    main()