canonical builds a sorted-by-frequency string representation:
let canonical s =
let chars = Array.make 26 0 in
for i = 0 to String.length s - 1 do
let k = Char.code s.[i] - Char.code 'a' in
if k >= 0 && k < 26 then chars.(k) <- chars.(k) + 1
done;
expand into a-z order via a Buffer
For 'eat', 'tea', 'ate' -> all canonicalise to 'aet'. For 'tan',
'nat' -> 'ant'. For 'bat' -> 'abt'.
group_anagrams folds the input, accumulating per-key string lists;
final answer is Hashtbl.length (number of distinct groups):
['eat'; 'tea'; 'tan'; 'ate'; 'nat'; 'bat'] -> 3 groups
99 baseline programs total.
giles
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