code: protected void greedyMatch() {
          for (int w = 0; w < dim; w++) {
              for (int j = 0; j < dim; j++) {
                  if (matchJobByWorker[w] == -1
                          && matchWorkerByJob[j] == -1
                          && costMatrix[w][j] - labelByWorker[w] - labelByJob[j] == 0) {
                      match(w, j);
                  }
              }
          }
      }
docs: Find a valid matching by greedily selecting among zero-cost matchings.
  This is a heuristic to jump-start the augmentation algorithm.