dost

Trivially improve distance_hierarchy
Parent cf8eb64
dkl9

dkl9 commited on 2025-190 04:12:28
Showing 1 changed files, with 3 additions and 2 deletions.

main.py
View file @ 8495c0a
... ... 
@@ -82,7 +82,7 @@ def cachey_nearest(distances: DistTable) -> IndSeq:
82 82 
         options.remove(best)
83 83 
     return seq
84 84
85 
-# good results, sketchy on a couple trials
85 
+# good results, sketchy on a couple trials: O(n^3)
86 86 
 def cachey_maximin(distances: DistTable) -> IndSeq:
87 87 
     seq = []
88 88 
     options = set(range(len(distances)))
... ... 
@@ -98,12 +98,13 @@ def cachey_maximin(distances: DistTable) -> IndSeq:
98 98 
         options.remove(best)
99 99 
     return seq
100 100
101 
+# empirically O(n^2 log n), but confusingly so
101 102 
 def distance_hierarchy(distances: DistTable) -> BinaryTree:
102 103 
     n = len(distances)
103 104 
     forest = [BinaryTree(i) for i in range(n)]
104 105 
     p = None
105 106 
     for (i, j) in sorted(
106 
-        ((i, j) for i in range(n) for j in range(n)),
107 
+        ((i, j) for i in range(n) for j in range(i)),
107 108 
         key=lambda ij: distances[ij[0]][ij[1]]
108 109 
     ):
109 110 
         p = forest[i].merge(forest[j])
110 111