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From: Ben Bear (benbearchen_at_[hidden])
Date: 2007-12-24 10:27:13

Herve: Merry Christmas

When I wrote test for next(prev)_combination_counts, I found a
difference with us. (Well, the version is also 2007-12-6)

I want to transform the `data' sequence, which is argument of
next_combination_counts, to the `value' sequence, which is the result
like next_mapping()'s output. But found that the data sequences are
lexicographical order, while the value sequences are not.

First, see the transforms. For example, the srouce values are {1, 2,
3, 4}, so the data sequence should have 4 elements, such as int
data[4]; the size of value sequence is 5, such as int value[5]. (The
transform order is reversed, so the data[4]={0, 0, 0, 5} will means
the smallest value sequence value[5]={1, 1, 1, 1, 1}.)

data[4] = {1, 1, 1, 2} <==> value[5] = {1, 1, 2, 3, 4}

void transform()
{
int* v = value;
int sv = 1; // source value
for (int* di = data + 4; di != data;)
{
--di;
for (int i = 0; i < *di; ++i)
*v++ = sv;
++sv;
}
}

With your implement, the example will be:
value sequence data sequence
1 1 1 1 1 0 0 0 5
1 1 1 1 2 0 0 1 4
1 1 1 2 2 0 0 2 3
1 1 2 2 2 0 0 3 2
1 2 2 2 2 0 0 4 1
2 2 2 2 2 0 0 5 0
1 1 1 1 3 0 1 0 4
...

My implement like this: (transform order is not reversed.)
value:[1 1 1] data: 3 0 0
value:[1 1 2] data: 2 1 0
value:[1 1 3] data: 2 0 1
value:[1 2 2] data: 1 2 0
value:[1 2 3] data: 1 1 1
value:[1 3 3] data: 1 0 2
value:[2 2 2] data: 0 3 0
value:[2 2 3] data: 0 2 1
value:[2 3 3] data: 0 1 2
value:[3 3 3] data: 0 0 3

The value sequences are lexicographical order, while the data sequences are not.

2007/12/24, Ben Bear <benbearchen_at_[hidden]>:
> Sorry. I had lost too many times.
>
>
> 2007/12/6, Hervé Brönnimann <hervebronnimann_at_[hidden]>:

>
> My test showed that a bug exists in prev_mapping(). The last sentence
> of prev_mapping() should be "return false;", but not "return true;".
> Date of the tested combination.hpp is 2007-12-6.
>
> I'll put my test tonight. It mainly test the increment/decrement of
> the sequences and the returned flags.
>