plus-gt.c
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/* X + Y > k */
int fd_plus_gt_propagate(fd_constraint this, fd_int revise)
{
fd_int other;
int other_idx;
int changed = 0;
other_idx = revise == VAR(this, 0) ? 1 : 0;
other = VAR(this, other_idx);
changed = _fd_var_del_le(this->constants[0] - _fd_var_max(other), revise);
if (changed && fd_domain_empty(revise))
return FD_NOSOLUTION;
// XXX: enqueue further updates here?
if (changed)
_fd_revise_connected(this, revise);
return FD_OK;
}
fd_constraint fd_plus_gt(fd_int x, fd_int y, int k)
{
fd_constraint c = _fd_constraint_new(2, 1);
if (c)
{
c->variables[0] = FD_INT2C_VAR(x); c->variables[1] = FD_INT2C_VAR(y);
c->constants[0] = k;
#ifdef CONSTRAINT_CLASS
c->kind = FD_CONSTR_PLUS_GT;
#else /* CONSTRAINT_CLASS */
c->propagator = fd_plus_gt_propagate;
#endif /* CONSTRAINT_CLASS */
_fd_var_add_constraint(x, c);
_fd_var_add_constraint(y, c);
_fd_add_constraint(c);
}
return c;
}