笛卡儿积运算_list.deletecharat-优快云博客

本文链接：https://blog.youkuaiyun.com/chang_p_x/article/details/103024727

本文深入探讨了一种基于递归的组合算法，该算法用于处理产品规格细节的列表，通过递归方式生成所有可能的组合结果。算法首先将每个产品规格的值转换为字符串形式，然后逐层递归，确保在每一层上都与前一层的组合进行连接，最终形成完整的组合列表。

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private static void recursive (List<ProductSpecDetail> specDetailList, List<String> result, int layer, StringBuilder curList) {
   List<List<String>> dimValue = new ArrayList<>();
   for (ProductSpecDetail detail : specDetailList) {
      Set<ProductSpecDetailValue> values = detail.getValues();
      List<String> di = new ArrayList<>();
      for (ProductSpecDetailValue value : values) {
         StringBuilder sb1 = new StringBuilder();
         sb1.append(value.getSpecId()).append(":").append(value.getSpecValueId());
         di.add(sb1.toString());
      }
      dimValue.add(di);
   }
   if (layer < dimValue.size() - 1) {
      if (dimValue.get(layer).size() == 0) {
         recursive(specDetailList, result, layer + 1, curList);
      } else {
         for (int i = 0; i < dimValue.get(layer).size(); i++) {
            StringBuilder list = curList;
            list = new StringBuilder().append(list).append(";").append(dimValue.get(layer).get(i));
            recursive(specDetailList, result, layer + 1, list);
         }
      }
   } else if (layer == dimValue.size() - 1) {
      if (dimValue.get(layer).size() == 0) {
         result.add(curList.toString());
      } else {
         for (int i = 0; i < dimValue.get(layer).size(); i++) {
            StringBuilder list = curList;
            list = new StringBuilder().append(list).append(";").append(dimValue.get(layer).get(i));
            list.deleteCharAt(0);
            result.add(list.toString());
         }
      }
   }
}