if (visited_num != -1) {
if (dot_output != nullptr) {
fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", this->previousPair_, visited_num,
if (visited_num != -1) {
if (dot_output != nullptr) {
fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", this->previousPair_, visited_num,