comefrom: <awangdev>350. Intersection of Two Arrays II_1.java
code: private Map<Integer, Integer> buildCountMap(int[] nums) {
  
          Map<Integer, Integer> map = new HashMap<>();
          for (int num : nums) {
              map.putIfAbsent(num, 0);
              map.put(num, map.get(num) + 1);
          }
          return map;
      }
masked: private Map < Integer , Integer > var_1 ( int [ ] var_2 ) {
    Map < Integer , Integer > var_5 = new HashMap < > ( ) ;
    for ( int var_6 : var_2 ) {
      var_5 . putIfAbsent ( var_6 , 0 ) ;
      var_5 . put ( var_6 , var_5 . get ( var_6 ) + 1 ) ;
    }
    return var_5 ;
  }
  