dost

Use a weird traversal of binary trees
Parent 956f128
dkl9

dkl9 commited on 2025-185 22:47:45
Showing 1 changed files, with 67 additions and 0 deletions.

main.py
View file @ 7c72f18
... ... 
@@ -6,6 +6,42 @@ Func: typing.TypeAlias = collections.abc.Callable
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 DistTable: typing.TypeAlias = list[list[float]]
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 IndSeq: typing.TypeAlias = list[int]
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+def tree_weight(x) -> int:
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+    if x is None:
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+        return 0
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+    elif isinstance(x, BinaryTree):
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+        return x.weight
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+    return 1
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+
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+class BinaryTree:
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+    def __init__(self, a, b=None):
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+        self.x = self.y = self.parent = None
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+        self.a = a
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+        self.b = b
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+        self.weight = tree_weight(a) + tree_weight(b)
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+        self.usage = 0
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+
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+    def __str__(self) -> str:
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+        return str(self.a) if self.b is None else f"({self.a} {self.b})"
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+
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+    def merge(self, other):
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+        a, b = self, other
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+        while a.parent:
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+            a = a.parent
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+        while b.parent:
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+            b = b.parent
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+        if a is b:
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+            return a
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+        parent = BinaryTree(a, b)
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+        a.parent = b.parent = parent
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+        return parent
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+
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+    def use(self):
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+        assert self.usage < self.weight
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+        self.usage += 1
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+        if self.parent:
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+            self.parent.use()
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+
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 def distance_table[T](points: list[T], metric: Func[[T, T], float]) -> DistTable:
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     return [[metric(x, y) for y in points] for x in points]
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... ... 
@@ -26,5 +62,36 @@ def greedy_min_seq(distances: DistTable, score_func: Func[[DistTable, IndSeq], f
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         options.remove(best)
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     return seq
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+def distance_hierarchy(distances: DistTable) -> BinaryTree:
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+    n = len(distances)
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+    forest = [BinaryTree(i) for i in range(n)]
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+    p = None
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+    for (i, j) in sorted(
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+        ((i, j) for i in range(n) for j in range(n)),
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+        key=lambda ij: distances[ij[0]][ij[1]]
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+    ):
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+        p = forest[i].merge(forest[j])
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+    return p
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+
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+def scattered_hierarchy(hierarchy: BinaryTree) -> IndSeq:
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+    seq = []
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+    while hierarchy.usage < hierarchy.weight:
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+        fb = hierarchy
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+        while fb.b is not None:
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+            ua = fb.a.usage / fb.a.weight
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+            ub = fb.b.usage / fb.b.weight
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+            if ua < ub:
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+                fb = fb.a
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+            elif ua == ub and fb.a.weight > fb.b.weight:
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+                fb = fb.a
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+            else:
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+                fb = fb.b
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+        fb.use()
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+        seq.append(fb.a)
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+    return seq
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+
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 dt: DistTable = distance_table([(0, 2), (3, 2), (4, 2), (5, 0), (0, 0)], math.dist)
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 print(greedy_min_seq(dt, score_total))
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+h: BinaryTree = distance_hierarchy(dt)
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+print(h)
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+print(scattered_hierarchy(h))
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