Hello Gecoders,
I'd like to perform a depth first search with a specific static variable
ordering. I have a matrix of integer variables and I want to label the
top row first, then the left column, then the rest of the matrix in
standard top-to-bottom, left-to-right order.
The naive search shown here gives a standard top-to-bottom,
left-to-right ordering:
class Problem : public Space {
IntVarArray cells;
Problem(int n) {
Matrix<IntVarArray> m(cells, n, n);
// ...
// set up constraints on cells via m
// ...
branch(*this, cells, INT_VAR_NONE, INT_VAR_MIN);
}
}
I have managed to achieve the ordering I want, like this (with the new
bits marked with comments):
class Problem : public Space {
IntVarArray cells;
IntVarArray ordering; // *** added this array ***
Problem(int n) {
Matrix<IntVarArray> m(cells, n, n);
// ...
// set up constraints on cells via m
// ...
// *** added this block ***
int index = 0;
for (int c = 0 ; c < n ; c++)
ordering[index++] = m(c,0);
for (int r = 1 ; r < n ; r++)
ordering[index++] = m(0,r);
for (int r = 1 ; r < n ; r++)
for (int c = 1 ; c < n ; c++)
ordering[index++] = m(c,r);
// *** search on "ordering" instead of "cells" ***
branch(*this, cells, INT_VAR_NONE, INT_VAR_MIN);
}
}
This seems to work. My question: is this the best way to do it? (It
just occurred to me that maybe it could be done using Slices -- is that
right?)
Thanks,
Chris
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