按多个字段分组，并使用Dart和Flutter获得最大值

class Person {
  String name;
  int age;
  double salary;

  Person(this.name, this.age, this.salary);
}

List<Person> persons = [
  Person('Alice', 25, 5000),
  Person('Bob', 30, 6000),
  Person('Alice', 35, 7000),
  Person('Bob', 40, 8000),
  Person('Alice', 45, 9000),
];

Map<String, Map<int, double>> groupAndFindMaxSalary(List<Person> persons) {
  return persons.fold({}, (Map<String, Map<int, double>> map, Person person) {
    map.putIfAbsent(person.name, () => {});
    map[person.name].putIfAbsent(person.age, () => 0);
    map[person.name][person.age] = map[person.name][person.age].clamp(person.salary, double.infinity);
    return map;
  });
}

void main() {
  Map<String, Map<int, double>> result = groupAndFindMaxSalary(persons);
  print(result);
}

{
  Alice: {25: 5000.0, 35: 7000.0, 45: 9000.0},
  Bob: {30: 6000.0, 40: 8000.0}
}