w->prb_color = f->prb_color; f->prb_color = PRB_BLACK; w->prb_link[0]->prb_color = PRB_BLACK; f->prb_link[0] = w->prb_link[1]; w->prb_link[1] = f; g->prb_link[g->prb_link[0] != f] = w; w->prb_parent = f->prb_parent; f->prb_parent = w; if (f->prb_link[0] != NULL) f->prb_link[0]->prb_parent = f;