Roger wrote:
> The bar is higher for prepend/append in-place.
OK, but since
name=: x,name
is logically equivalent to:
name=: name,x O(1) space, O(1) time
name=: i A. name O(1) space, O(1) time
for some i , then all that remains is to discover a function foo such that:
name ((A.~ foo) -: (|.~ >:)) #x
and we can have prepend-in-place in O(1) space, O(1) time. My brief
investigations have led to no obvious definition of foo .
Here's a table of the first few required outputs of foo , where the
horizontal axis is (#name) and the vertical is (#x) :
A.@:(|. i.)"0 table~ i. 10
+-------------+-----------------------------------+
|A.@:(|. i.)"0|0 1 2 3 4 5 6 7 8 9|
+-------------+-----------------------------------+
|0 |0 0 0 0 0 0 0 0 0 0|
|1 |0 0 1 3 9 33 153 873 5913 46233|
|2 |0 0 0 4 16 64 304 1744 11824 92464|
|3 |0 0 1 0 18 90 450 2610 17730 138690|
|4 |0 0 0 3 0 96 576 3456 23616 184896|
|5 |0 0 1 4 9 0 600 4200 29400 231000|
|6 |0 0 0 0 16 33 0 4320 34560 276480|
|7 |0 0 1 3 18 64 153 0 35280 317520|
|8 |0 0 0 4 0 90 304 873 0 322560|
|9 |0 0 1 0 9 96 450 1744 5913 0|
+-------------+-----------------------------------+
-Dan
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