Dart 语言实现唯一出现次数的算法 - uniqueOccurrences 函数

import\u0027dart:collection\u0027;

bool uniqueOccurrences(List\u003Cint\u003E arr) { Map\u003Cint, int\u003E occur = HashMap\u003Cint, int\u003E(); for (int x in arr) { occur[x] = occur.containsKey(x) ? occur[x] + 1 : 1; } Set\u003Cint\u003E times = HashSet\u003Cint\u003E(); for (MapEntry\u003Cint, int\u003E x in occur.entries) { times.add(x.value); } return times.length == occur.length; }