本文实例讲述了Java笛卡尔积算法原理与实现方法。分享给大家供大家参考，具体如下：
笛卡尔积算法的Java实现：
（1）循环内，每次只有一列向下移一个单元格，就是CounterIndex指向的那列。
（2）如果该列到尾部了，则这列index重置为0，而CounterIndex则指向前一列，相当于进位，把前列的index加一。
（3）最后，由生成的行数来控制退出循环。
public class Test {
private static String[] aa = { "aa1", "aa2" };
private static String[] bb = { "bb1", "bb2", "bb3" };
private static String[] cc = { "cc1", "cc2", "cc3", "cc4" };
private static String[][] xyz = { aa, bb, cc };
private static int counterIndex = xyz.length - 1;
private static int[] counter = { 0, 0, 0 };
public static void main(String[] args) throws Exception {
for (int i = 0; i < aa.length * bb.length * cc.length; i++) {
System.out.print(aa[counter[0]]);
System.out.print("t");
System.out.print(bb[counter[1]]);
System.out.print("t");
System.out.print(cc[counter[2]]);
System.out.println();
handle();
}
}
public static void handle() {
counter[counterIndex]++;
if (counter[counterIndex] >= xyz[counterIndex].length) {
counter[counterIndex] = 0;
counterIndex--;
if (counterIndex >= 0) {
handle();
}
counterIndex = xyz.length - 1;
}
}
}
输出共2*3*4=24行：
aa1 bb1 cc1 aa1 bb1 cc2 aa1 bb1 cc3 aa1 bb1 cc4 aa1 bb2 cc1 aa1 bb2 cc2 aa1 bb2 cc3 aa1 bb2 cc4 aa1 bb3 cc1 aa1 bb3 cc2 aa1 bb3 cc3 aa1 bb3 cc4 aa2 bb1 cc1 aa2 bb1 cc2 aa2 bb1 cc3 aa2 bb1 cc4 aa2 bb2 cc1 aa2 bb2 cc2 aa2 bb2 cc3 aa2 bb2 cc4 aa2 bb3 cc1 aa2 bb3 cc2 aa2 bb3 cc3 aa2 bb3 cc4
最近碰到了一个笛卡尔积的算法要求，比如传递过来的参数是"1,3,6,7==4,5,8,9==3,4==43,45,8,9==35,4"，则返回的是一个list，如[1,4,3,43,35][1,4,3,43,4][1,4,3,45,35]……，该list包含是4*4*2*4*2=256个元素，现在的思路是这样的：
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class DescartesTest {
public static void main(String[] args) {
// TODO Auto-generated method stub
String str ="1,3,6,7==4,5,8,9==3,4==43,45,8,9==35,4";
List result = descartes(str);
System.out.println(result);
}
@SuppressWarnings("rawtypes")
public static List descartes(String str) {
String[] list = str.split("==");
List strs = new ArrayList();
for(int i=0;i
运行结果输出：
[[1, 3, 6, 7], [4, 5, 8, 9], [3, 4], [43, 45, 8, 9], [35, 4]]
[1,4,3,43,35, 1,4,3,43,4, 1,4,3,45,35, 1,4,3,45,4, 1,4,3,8,35, 1,4,3,8,4, 1,4,3,9,35, 1,4,3,9,4, 1,4,4,43,35, 1,4,4,43,4, 1,4,4,45,35, 1,4,4,45,4, 1,4,4,8,35, 1,4,4,8,4, 1,4,4,9,35, 1,4,4,9,4, 1,5,3,43,35, 1,5,3,43,4, 1,5,3,45,35, 1,5,3,45,4, 1,5,3,8,35, 1,5,3,8,4, 1,5,3,9,35, 1,5,3,9,4, 1,5,4,43,35, 1,5,4,43,4, 1,5,4,45,35, 1,5,4,45,4, 1,5,4,8,35, 1,5,4,8,4, 1,5,4,9,35, 1,5,4,9,4, 1,8,3,43,35, 1,8,3,43,4, 1,8,3,45,35, 1,8,3,45,4, 1,8,3,8,35, 1,8,3,8,4, 1,8,3,9,35, 1,8,3,9,4, 1,8,4,43,35, 1,8,4,43,4, 1,8,4,45,35, 1,8,4,45,4, 1,8,4,8,35, 1,8,4,8,4, 1,8,4,9,35, 1,8,4,9,4, 1,9,3,43,35, 1,9,3,43,4, 1,9,3,45,35, 1,9,3,45,4, 1,9,3,8,35, 1,9,3,8,4, 1,9,3,9,35, 1,9,3,9,4, 1,9,4,43,35, 1,9,4,43,4, 1,9,4,45,35, 1,9,4,45,4, 1,9,4,8,35, 1,9,4,8,4, 1,9,4,9,35, 1,9,4,9,4, 3,4,3,43,35, 3,4,3,43,4, 3,4,3,45,35, 3,4,3,45,4, 3,4,3,8,35, 3,4,3,8,4, 3,4,3,9,35, 3,4,3,9,4, 3,4,4,43,35, 3,4,4,43,4, 3,4,4,45,35, 3,4,4,45,4, 3,4,4,8,35, 3,4,4,8,4, 3,4,4,9,35, 3,4,4,9,4, 3,5,3,43,35, 3,5,3,43,4, 3,5,3,45,35, 3,5,3,45,4, 3,5,3,8,35, 3,5,3,8,4, 3,5,3,9,35, 3,5,3,9,4, 3,5,4,43,35, 3,5,4,43,4, 3,5,4,45,35, 3,5,4,45,4, 3,5,4,8,35, 3,5,4,8,4, 3,5,4,9,35, 3,5,4,9,4, 3,8,3,43,35, 3,8,3,43,4, 3,8,3,45,35, 3,8,3,45,4, 3,8,3,8,35, 3,8,3,8,4, 3,8,3,9,35, 3,8,3,9,4, 3,8,4,43,35, 3,8,4,43,4, 3,8,4,45,35, 3,8,4,45,4, 3,8,4,8,35, 3,8,4,8,4, 3,8,4,9,35, 3,8,4,9,4, 3,9,3,43,35, 3,9,3,43,4, 3,9,3,45,35, 3,9,3,45,4, 3,9,3,8,35, 3,9,3,8,4, 3,9,3,9,35, 3,9,3,9,4, 3,9,4,43,35, 3,9,4,43,4, 3,9,4,45,35, 3,9,4,45,4, 3,9,4,8,35, 3,9,4,8,4, 3,9,4,9,35, 3,9,4,9,4, 6,4,3,43,35, 6,4,3,43,4, 6,4,3,45,35, 6,4,3,45,4, 6,4,3,8,35, 6,4,3,8,4, 6,4,3,9,35, 6,4,3,9,4, 6,4,4,43,35, 6,4,4,43,4, 6,4,4,45,35, 6,4,4,45,4, 6,4,4,8,35, 6,4,4,8,4, 6,4,4,9,35, 6,4,4,9,4, 6,5,3,43,35, 6,5,3,43,4, 6,5,3,45,35, 6,5,3,45,4, 6,5,3,8,35, 6,5,3,8,4, 6,5,3,9,35, 6,5,3,9,4, 6,5,4,43,35, 6,5,4,43,4, 6,5,4,45,35, 6,5,4,45,4, 6,5,4,8,35, 6,5,4,8,4, 6,5,4,9,35, 6,5,4,9,4, 6,8,3,43,35, 6,8,3,43,4, 6,8,3,45,35, 6,8,3,45,4, 6,8,3,8,35, 6,8,3,8,4, 6,8,3,9,35, 6,8,3,9,4, 6,8,4,43,35, 6,8,4,43,4, 6,8,4,45,35, 6,8,4,45,4, 6,8,4,8,35, 6,8,4,8,4, 6,8,4,9,35, 6,8,4,9,4, 6,9,3,43,35, 6,9,3,43,4, 6,9,3,45,35, 6,9,3,45,4, 6,9,3,8,35, 6,9,3,8,4, 6,9,3,9,35, 6,9,3,9,4, 6,9,4,43,35, 6,9,4,43,4, 6,9,4,45,35, 6,9,4,45,4, 6,9,4,8,35, 6,9,4,8,4, 6,9,4,9,35, 6,9,4,9,4, 7,4,3,43,35, 7,4,3,43,4, 7,4,3,45,35, 7,4,3,45,4, 7,4,3,8,35, 7,4,3,8,4, 7,4,3,9,35, 7,4,3,9,4, 7,4,4,43,35, 7,4,4,43,4, 7,4,4,45,35, 7,4,4,45,4, 7,4,4,8,35, 7,4,4,8,4, 7,4,4,9,35, 7,4,4,9,4, 7,5,3,43,35, 7,5,3,43,4, 7,5,3,45,35, 7,5,3,45,4, 7,5,3,8,35, 7,5,3,8,4, 7,5,3,9,35, 7,5,3,9,4, 7,5,4,43,35, 7,5,4,43,4, 7,5,4,45,35, 7,5,4,45,4, 7,5,4,8,35, 7,5,4,8,4, 7,5,4,9,35, 7,5,4,9,4, 7,8,3,43,35, 7,8,3,43,4, 7,8,3,45,35, 7,8,3,45,4, 7,8,3,8,35, 7,8,3,8,4, 7,8,3,9,35, 7,8,3,9,4, 7,8,4,43,35, 7,8,4,43,4, 7,8,4,45,35, 7,8,4,45,4, 7,8,4,8,35, 7,8,4,8,4, 7,8,4,9,35, 7,8,4,9,4, 7,9,3,43,35, 7,9,3,43,4, 7,9,3,45,35, 7,9,3,45,4, 7,9,3,8,35, 7,9,3,8,4, 7,9,3,9,35, 7,9,3,9,4, 7,9,4,43,35, 7,9,4,43,4, 7,9,4,45,35, 7,9,4,45,4, 7,9,4,8,35, 7,9,4,8,4, 7,9,4,9,35, 7,9,4,9,4]
递归算法：
public static void fn(List list,String[] arr,String str){
//迭代list
List li = new ArrayList();
for(int i=0;i
更多关于java算法相关内容感兴趣的读者可查看本站专题：《Java数据结构与算法教程》、《Java操作DOM节点技巧总结》、《Java文件与目录操作技巧汇总》和《Java缓存操作技巧汇总》
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