maze-solving-qwen35 / src /maze_lab /difficulty.py
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Initial upload of Qwen3.5 maze-solving experiments
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"""A fixed difficulty ladder on a FIXED 13x13 grid.
The point: hold the grid size constant so prompt length and visual scale
never vary, and let difficulty come only from the route itself -- how long
it is, and how many places along it the solver can take a wrong turn.
Two measured properties define a level:
moves length of the (unique) S->E route
decision_pts cells ON the route with 3+ open neighbours, i.e. places
where the solver must actually choose. A corridor cell
with two exits is not a decision; it's bookkeeping.
Both are read off the finished maze by `analyse`, never assumed from the
generator's arguments -- `n_traps=6` does not mean six wrong turns landed
on the route (see generate_graded_maze's docstring for how far apart those
two numbers can be).
Why 13x13 is exactly rooms=6: the room-grid construction always yields an
odd 2*rooms+1 size, and 2*6+1 == 13 lands on it with no padding, so the
whole grid is usable (no inert wall margin eating difficulty).
The seeds in LEVELS were found by `python -m maze_lab.difficulty --search`
and pasted back here, so the suite is fixed: same mazes on every run,
every machine. Re-running --search reproduces them exactly.
"""
from __future__ import annotations
import json
from dataclasses import dataclass
from pathlib import Path
from .maze_generator import generate_graded_maze, open_fraction
ROOMS = 6 # -> exactly 13x13, no padding
GRID_SIZE = 2 * ROOMS + 1
_DIRS = ((-1, 0), (1, 0), (0, -1), (0, 1))
@dataclass(frozen=True)
class Level:
"""A difficulty rung. `moves` and `decision_pts` are INCLUSIVE ranges a
candidate maze must land in to qualify; the generator arguments below
them are only what the search feeds in while hunting for such a maze."""
name: str
moves: tuple # (min, max) route length
decision_pts: tuple # (min, max) real choices on the route
target_moves: int # generator: route-length cap
n_traps: int # generator: traps to attempt
max_trap_depth: int # generator: how deep each may run
LEVEL_SPECS = {
1: Level("easy", moves=(12, 18), decision_pts=(0, 1), target_moves=18, n_traps=1, max_trap_depth=1),
2: Level("medium", moves=(20, 28), decision_pts=(2, 3), target_moves=28, n_traps=3, max_trap_depth=2),
3: Level("hard", moves=(30, 36), decision_pts=(3, 4), target_moves=36, n_traps=5, max_trap_depth=3),
4: Level("very_hard", moves=(38, 44), decision_pts=(5, 9), target_moves=44, n_traps=8, max_trap_depth=4),
}
# Verified seeds, 3 per level -- filled in by --search, see module docstring.
LEVELS: dict[int, list[int]] = {
1: [0, 1, 2], # easy: 18mv/0dp, 18mv/0dp, 18mv/0dp
2: [3, 4, 5], # medium: 28mv/3dp, 28mv/2dp, 24mv/2dp
3: [8, 9, 10], # hard: 36mv/3dp, 32mv/3dp, 36mv/3dp
4: [83, 565, 754], # very_hard: 44mv/5dp, 44mv/5dp, 44mv/5dp
}
def build(level: int, seed: int):
"""The one place generator arguments get applied, so a level's mazes
can never drift apart between the search and the benchmark run."""
spec = LEVEL_SPECS[level]
return generate_graded_maze(seed, rooms=ROOMS, target_moves=spec.target_moves,
n_traps=spec.n_traps, max_trap_depth=spec.max_trap_depth)
def _exits(m, pos) -> int:
return sum(1 for dr, dc in _DIRS if m.is_open((pos[0] + dr, pos[1] + dc)))
def analyse(m) -> dict:
"""Measure a finished maze: route length, real decision points, how far
the deepest wrong turn runs, and open-floor density."""
solution = m.bfs_path_to_goal(m.start)
path, pos = [m.start], m.start
for mv in solution:
pos, _ = m.step(pos, mv)
path.append(pos)
path_set = set(path)
decision_pts = sum(1 for p in path if _exits(m, p) >= 3)
deepest = 0
for p in path:
for dr, dc in _DIRS:
nbr = (p[0] + dr, p[1] + dc)
if not m.is_open(nbr) or nbr in path_set:
continue
# flood the wrong turn, staying off the route, to see how many
# cells the solver would burn before the dead end is obvious
seen, stack, depth = {p, nbr}, [(nbr, 1)], 0
while stack:
cur, d = stack.pop()
depth = max(depth, d)
for ddr, ddc in _DIRS:
nxt = (cur[0] + ddr, cur[1] + ddc)
if m.is_open(nxt) and nxt not in seen and nxt not in path_set:
seen.add(nxt)
stack.append((nxt, d + 1))
deepest = max(deepest, depth)
return {"moves": len(solution), "decision_pts": decision_pts,
"deepest_wrong_turn": deepest, "open": open_fraction(m),
"solution": solution}
def qualifies(level: int, m) -> bool:
spec = LEVEL_SPECS[level]
st = analyse(m)
return (spec.moves[0] <= st["moves"] <= spec.moves[1]
and spec.decision_pts[0] <= st["decision_pts"] <= spec.decision_pts[1])
def search_seeds(level: int, want: int = 3, limit: int = 4000, exclude=()) -> list:
"""First `want` seeds whose maze actually measures up to the level.
Deterministic: same seeds every run.
`exclude` keeps a seed from being reused on another level. The carved
tree depends only on (seed, rooms), so the same seed at two levels
gives two routes through the SAME tree -- related layouts, which would
make levels look alike for no good reason."""
found = []
for seed in range(limit):
if seed in exclude:
continue
if qualifies(level, build(level, seed)):
found.append(seed)
if len(found) == want:
break
return found
def suite():
"""The full fixed benchmark: [(level, seed, maze, stats), ...]."""
out = []
for level in sorted(LEVELS):
for seed in LEVELS[level]:
m = build(level, seed)
out.append((level, seed, m, analyse(m)))
return out
PROJECT_ROOT = Path(__file__).resolve().parents[2]
VIEWER = PROJECT_ROOT / "web" / "viewer.html"
_BEGIN, _END = "/* SUITE:BEGIN */", "/* SUITE:END */"
def export_viewer(path: Path = VIEWER) -> int:
"""Write the suite into viewer.html between its SUITE markers.
The mazes are EXPORTED rather than regenerated in the page because the
viewer's JS uses its own PRNG -- same algorithm, different random
stream -- so a JS rebuild would produce plausible lookalikes, not the
mazes benchmark.py actually runs. Re-run this after changing
LEVEL_SPECS, LEVELS, or the generator.
"""
rows = []
for level, seed, m, st in suite():
rows.append({"level": level, "level_name": LEVEL_SPECS[level].name, "seed": seed,
"grid": list(m.grid), "start": list(m.start), "goal": list(m.goal),
"moves": st["moves"], "decision_pts": st["decision_pts"],
"deepest_wrong_turn": st["deepest_wrong_turn"],
"open": round(st["open"], 4), "solution": st["solution"]})
html = path.read_text()
if _BEGIN not in html or _END not in html:
raise SystemExit(f"{path} has no {_BEGIN} ... {_END} block to write into")
head, rest = html.split(_BEGIN, 1)
_stale, tail = rest.split(_END, 1)
body = "\nconst SUITE = " + json.dumps(rows, indent=2) + ";\n"
path.write_text(head + _BEGIN + body + _END + tail)
return len(rows)
def _main():
import argparse
ap = argparse.ArgumentParser(description="Inspect or rebuild the difficulty ladder.")
ap.add_argument("--search", action="store_true",
help="hunt for qualifying seeds and print a LEVELS dict to paste back")
ap.add_argument("--show", action="store_true", help="print every maze in the suite")
ap.add_argument("--export-viewer", action="store_true",
help="write the suite into viewer.html so the browser shows these exact mazes")
args = ap.parse_args()
if args.export_viewer:
n = export_viewer()
print(f"wrote {n} mazes into {VIEWER}")
return
if args.search:
print("LEVELS = {")
used = set()
for level in sorted(LEVEL_SPECS):
seeds = search_seeds(level, exclude=used)
used.update(seeds)
stats = [analyse(build(level, s)) for s in seeds]
desc = ", ".join(f"{s['moves']}mv/{s['decision_pts']}dp" for s in stats)
print(f" {level}: {seeds}, # {LEVEL_SPECS[level].name}: {desc}")
print("}")
return
print(f"{'lvl':>3} {'name':<10} {'seed':>5} {'grid':>7} {'moves':>6} {'decisions':>10} "
f"{'deepest':>8} {'open':>6}")
for level, seed, m, st in suite():
print(f"{level:>3} {LEVEL_SPECS[level].name:<10} {seed:>5} "
f"{len(m.grid)}x{len(m.grid[0]):<4} {st['moves']:>6} {st['decision_pts']:>10} "
f"{st['deepest_wrong_turn']:>8} {st['open']*100:>5.0f}%")
if args.show:
print(m.render(), "\n")
if __name__ == "__main__":
_main()