笛卡爾積大家想必都比較了解,在這裏不做理論上的贅述了,直接上代碼,如下所示:
- public class Test1 {
- @SuppressWarnings({ "rawtypes", "unchecked" })
- public static void main(String[] args) {
- ArrayList l1 = new ArrayList();
- l1.add(1);
- l1.add(2);
- l1.add(3);
- ArrayList l2 = new ArrayList();
- l2.add("a");
- l2.add("b");
- ArrayList l3 = new ArrayList();
- l3.add("+");
- l3.add("-");
- ArrayList ls = new ArrayList();
- ls.add(l1);
- ls.add(l2);
- ls.add(l3);
- List list = Dikaerji0(ls);
- system.out.println(list.size());
- for (Object object : list) {
- System.out.println(object);
- }
- }
- @SuppressWarnings({ "rawtypes", "unchecked" })
- public static ArrayList Dikaerji0(ArrayList al0) {
- ArrayList a0 = (ArrayList) al0.get(0);// l1
- ArrayList result = new ArrayList();// 組合的結果
- for (int i = 1; i < al0.size(); i++) {
- ArrayList a1 = (ArrayList) al0.get(i);
- ArrayList temp = new ArrayList();
- // 每次先計算兩個集合的笛卡爾積,然後用其結果再與下一個計算
- for (int j = 0; j < a0.size(); j++) {
- for (int k = 0; k < a1.size(); k++) {
- ArrayList cut = new ArrayList();
- if (a0.get(j) instanceof ArrayList) {
- cut.addAll((ArrayList) a0.get(j));
- } else {
- cut.add(a0.get(j));
- }
- if (a1.get(k) instanceof ArrayList) {
- cut.addAll((ArrayList) a1.get(k));
- } else {
- cut.add(a1.get(k));
- }
- temp.add(cut);
- }
- }
- a0 = temp;
- if (i == al0.size() - 1) {
- result = temp;
- }
- }
- return result;
- }
- }
Tags: Object public result 笛卡爾 Java
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