用二进制的方法，

        public static ArrayList<ArrayList<Integer>> generateCombinations(Array
List <Integer> array) {
                ArrayList<ArrayList<Integer>> combinations = new
ArrayList<>();
                int n = array.size();
                int max = (1 << n); // 2^n

                for (int i = 1; i < max; i++) {
                        ArrayList<Integer> combination = new ArrayList<>();
                        for (int j = 0; j < n; j++) {
                                if ((i & (1 << j)) != 0) {
                                        combination.add(array.get(j));
                                }
                        }
                        combinations.add(combination);
                }

                return combinations;
        }



【 在 iStudy 的大作中提到: 】
: a,b,c,d四个对象
: 我要生成a,b,c,d的全组合===C(4,1)+C(4,2)+C(4,3)+C(4,4)
: 结果就是输出 {a,b,c,d, ab,ac,ad,bc,bd,cd,abc,abd,acd,bcd,abcd}
: ...................
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FROM 119.139.196.*