Re: Two recursive calls inside of a recursive function

From:
"Jim Langston" <tazmaster@rocketmail.com>
Newsgroups:
comp.lang.c++
Date:
Mon, 10 Mar 2008 14:24:17 -0700
Message-ID:
<hGhBj.522$PO.134@newsfe06.lga>
n00m wrote:

This combined with the lack of return-value
makes me wonder what the function is supposed to accomplish.


It's for counting the number of ways to fill a given grid (7x8) with
ciphers 0..6
with all 28 dominos bones. E.g., the answers for these 2 grids:

2
0 3 0 2 2 0 2 3
1 5 6 5 5 1 2 2
3 4 1 4 5 4 4 4
6 6 1 0 5 2 3 0
4 0 3 2 4 1 6 0
1 4 1 5 6 6 3 0
1 2 6 5 5 6 3 3

5 3 1 0 0 1 6 3
0 2 0 4 1 2 5 2
1 5 3 5 6 4 6 4
0 5 0 2 0 4 6 2
4 5 3 6 0 6 1 1
2 3 5 3 4 4 5 3
2 1 1 6 6 2 4 3

are 18 and 1.

Initially I wrote it in Pascal (in that the code works absolutely as
expected, so to speak).


Pascal would pass the entire array to the function, in C and C++ there is no
way to pass a native array as a parameter, only some pointer type ( int[],
int*, etc..). If you want to emulate the way Pascal is doing it, you need
to make a copy of the array and pass that, which is where vector should work
for you.

Consider:
#include <vector>
#include <iostream>

typedef std::vector<std::vector<int> > DataType;

void foo(short sch, DataType oc, DataType a, short p, short q, short fl)
{
    // Etc...
}

int main()
{
    DataType a;

    // Size our Data to 10 by 10
    for ( size_t i = 0; i < 10; ++i )
        a.push_back( std::vector<int>(10) );

    for ( size_t i = 0; i < 10; ++i)
        for (size_t j = 0; j < 10; ++j)
            a[i][j] = 7;

    // This makes a copy
    DataType oc = a;

    for ( size_t i = 0; i < 8; ++i) {
        oc[i][7]=1; oc[7][i]=1;
    }

    // Etc...

    // Now, we want to pass a copy to foo, not the original.
    // So make a copy.

    DataType OCCopy = oc;
    DataType ACopy = a;
    foo(1,OCCopy,ACopy,1,1,1);

    // Reset our copies
    OCCopy = oc;
    ACopy = a;
    foo(1,OCCopy,ACopy,1,1,1);

}

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