笛卡尔积算法「建议收藏」

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/** * 生成笛卡尔积 * @param dimvalue * @param result * @param layer * @param curList */
private static void descartes(List<List<String>> dimvalue, List<List<String>> result, int layer, List<String> curList) { 

if (layer < dimvalue.size() - 1) { 

if (dimvalue.get(layer).size() == 0) { 

descartes(dimvalue, result, layer + 1, curList);
} else { 

for (int i = 0; i < dimvalue.get(layer).size(); i++) { 

List<String> list = new ArrayList<>(curList);
list.add(dimvalue.get(layer).get(i));
descartes(dimvalue, result, layer + 1, list);
}
}
} else if (layer == dimvalue.size() - 1) { 

if (dimvalue.get(layer).size() == 0) { 

result.add(curList);
} else { 

for (int i = 0; i < dimvalue.get(layer).size(); i++) { 

List<String> list = new ArrayList<>(curList);
list.add(dimvalue.get(layer).get(i));
result.add(list);
}
}
}
}
/** * 调用生成列表 * @param list * @return */
public static List<String> result(List<List<String>> list){ 

List<List<String>> result = new ArrayList<>();
descartes(list, result, 0, new ArrayList<>());
//重组数据
List<String> data=new ArrayList<>();
result.forEach(oList->{ 

StringBuilder sb=new StringBuilder();
for(int i=0;i<oList.size();i++){ 

sb.append(oList.get(i));
if(i!=oList.size()-1){ 

sb.append(",");
}
}
data.add(sb.toString());
});
return data;
}