Dart列表的并集/交集

List<int> list1 = [1, 2, 3, 4];
List<int> list2 = [3, 4, 5, 6];

List<int> union(List<int> list1, List<int> list2) {
  Set<int> set = new Set<int>.from(list1);
  set.addAll(list2);
  return set.toList();
}

void main() {
  print(union(list1, list2)); // 输出: [1, 2, 3, 4, 5, 6]
}

List<int> list1 = [1, 2, 3, 4];
List<int> list2 = [3, 4, 5, 6];

List<int> intersection(List<int> list1, List<int> list2) {
  Set<int> set1 = new Set<int>.from(list1);
  Set<int> set2 = new Set<int>.from(list2);
  set1.retainWhere((element) => set2.contains(element));
  return set1.toList();
}

void main() {
  print(intersection(list1, list2)); // 输出: [3, 4]
}

List<int> union(List<int> list1, List<int> list2) {
  Set<int> set = new Set<int>();
  if (list1 != null) set.addAll(list1);
  if (list2 != null) set.addAll(list2);
  return set.toList();
}

List<int> intersection(List<int> list1, List<int> list2) {
  if (list1 == null || list2 == null) return [];
  Set<int> set1 = new Set<int>.from(list1);
  Set<int> set2 = new Set<int>.from(list2);
  set1.retainWhere((element) => set2.contains(element));
  return set1.toList();
}