baseline

2026-09-12 16:58:25 +08:00
parent 1fa2264a17
commit 892451dca9
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+"""问题二近似最优参考：在保证接收盘内做稠密网格枚举。
+
+目标函数与生产实现一致（最坏后验包围半径 + 移动时间同分决胜），但候选点
+取自**均匀网格**而非环形采样族，因此可用来检验生产采样是否接近该目标下的
+网格最优。注意这是"同一目标下的网格参考"，不是连续问题的严格全局最优。
+"""
+
+from __future__ import annotations
+
+import math
+
+from mcm26b.config import ProblemConfig
+from mcm26b.planner import (_worst_posterior_radius, safe_disk_radius)
+
+from project.common import Method, problem_config
+from project.q2.region import first_bearing_region
+
+METHOD = Method(
+    key="reference",
+    name="保证接收盘内网格枚举",
+    kind="reference",
+    note="同一目标下的稠密网格参考，非连续全局最优",
+)
+GRID_SIDES = 9
+WITNESS_SPACING_M = 150.0
+
+
+def candidate(case: dict, config: ProblemConfig | None = None) -> dict:
+    config = config or problem_config()
+    region = first_bearing_region(case, config)
+    station = (case["station"][0], case["station"][1])
+    center = region.mec()[0]
+    safe = safe_disk_radius(region, config)
+    if safe < 0:
+        return _payload(center, region, config, station, "无保证接收盘：退回 MEC 圆心")
+
+    field, search = config.field, config.search
+    half_angle = field.bearing_error_half_deg + search.bearing_rounding_margin_deg
+    witnesses = region.witnesses(WITNESS_SPACING_M)
+    step = 2.0 * safe / (GRID_SIDES - 1)
+    best_key, best_point, best_worst = None, center, None
+    for i in range(GRID_SIDES):
+        for j in range(GRID_SIDES):
+            point = (center[0] - safe + i * step, center[1] - safe + j * step)
+            if math.dist(point, center) > safe + 1e-9:
+                continue
+            worst = _worst_posterior_radius(region, point, witnesses, half_angle,
+                                            field.near_radius_m, search.polygon_sides)
+            move = math.dist(station, point) / config.cost.speed_mps
+            key = (round(worst, 6), round(move, 6))
+            if best_key is None or key < best_key:
+                best_key, best_point, best_worst = key, point, worst
+    return _payload(best_point, region, config, station,
+                    f"安全盘网格 {GRID_SIDES}×{GRID_SIDES} 取最坏后验最小",
+                    worst_value=best_worst)
+
+
+def _payload(point, region, config, station, reason, worst_value=None) -> dict:
+    return {
+        "method": METHOD.key,
+        "position": [round(point[0], 4), round(point[1], 4)],
+        "worst_posterior_radius_m": worst_value,
+        "move_cost_s": math.dist(station, point) / config.cost.speed_mps,
+        "safe_disk_radius_m": safe_disk_radius(region, config),
+        "initial_radius_m": region.mec()[1],
+        "reason": reason,
+    }