<awangdev>743. Network Delay Time_2.java
private Map<Integer, List<int[]>> buildGraph(int[][] times) {

        Map<Integer, List<int[]>> graph = new HashMap<>();
        for (int[] record : times) {
            graph.putIfAbsent(record[0], new ArrayList<>());
            graph.get(record[0]).add(record);
        }
        return graph;
    }
private Map < Integer , List < int [ ] >> var_2 ( int [ ] [ ] var_3 ) {
  Map < Integer , List < int [ ] >> var_6 = new HashMap < > ( ) ;
  for ( int [ ] var_7 : var_3 ) {
    var_6 . putIfAbsent ( var_7 [ 0 ] , new ArrayList < > ( ) ) ;
    var_6 . get ( var_7 [ 0 ] ) . add ( var_7 ) ;
  }
  return var_6 ;
}
