Java 二维数组/集合生成排列组合矩阵

写在前面

Question：给出任意一个二维数组，要求输出数组元素的所有排列组合
例如:

String[][] array = {{"a", "b", "c"}, {"d", "e", "f", "g"}, {"h", "i"}};

**输出**：

adh,aeh,afh,agh,adi,aei,afi,agi
bdh,beh,bfh,bgh,bdi,bei,bfi,bgi
cdh,ceh,cfh,cgh,cdi,cei,cfi,cgi

代码

二维数组矩阵

	/**
     * @param array 目标数组
     * @return 矩阵结果
     * @description: 根据给定二维数组，输出排列组合矩阵
     */
    public String[][] generateMatrix(String[][] array) {
        ArrayList<Integer> lengthArr = new ArrayList<>();
        ArrayList<Integer> productArr = new ArrayList<>();
        int length = 1;
        for (int i = 0; i < array.length; i++) {
            int len = array[i].length;
            lengthArr.add(len);
            int product = i == 0 ? 1 : array[i - 1].length * productArr.get(i - 1);
            productArr.add(product);
            length *= len;
        }
        String[][] result = new String[array.length][length / array.length];
        for (int i = 0; i < length; i++) {
            StringBuilder item = new StringBuilder();
            for (int j = 0; j < array.length; j++) {
                item.append(array[j][(int) (Math.floor(i / productArr.get(j)) % lengthArr.get(j))]);
            }
            int index1 = i % array.length;
            int index2 = i / array.length;
            result[index1][index2] = item.toString();
        }
        return result;
    }
    

二维数组集合

    /**
     * @param array 目标数组
     * @return 排列组合结果
     * @description: 根据给定二维数组，输出排列组合结果
     */
    public ArrayList<String> generateList(String[][] array) {
        ArrayList<Integer> lengthArr = new ArrayList<>();
        ArrayList<Integer> productArr = new ArrayList<>();
        ArrayList<String> result = new ArrayList<>();
        int length = 1;
        for (int i = 0; i < array.length; i++) {
            int len = array[i].length;
            lengthArr.add(len);
            int product = i == 0 ? 1 : array[i - 1].length * productArr.get(i - 1);
            productArr.add(product);
            length *= len;
        }
        for (int i = 0; i < length; i++) {
            StringBuilder item = new StringBuilder();
            for (int j = 0; j < array.length; j++) {
                item.append(array[j][(int) (Math.floor(i / productArr.get(j)) % lengthArr.get(j))]);
            }
            result.add(item.toString());
        }
        return result;
    }

测试代码

	@Test
    public void testJava() {
        String[] row1 = new String[]{"a", "b", "c"};
        String[] row2 = new String[]{"d", "e", "f", "g"};
        String[] row3 = new String[]{"h", "i"};
        String[][] array = {row1, row2, row3};

        //获取矩阵结果
        String[][] matrix = generateMatrix(array);
        for (int i = 0; i < matrix.length; i++) {
            for (int j = 0; j < matrix[i].length; j++) {
                System.out.print(matrix[i][j] + ",");
            }
            System.out.println();
        }
        
		System.out.println("**********************************************************");

        //获取集合
        ArrayList<String> list = generateList(array);
        for (int i = 0; i < list.size(); i++) {
            System.out.println(list.get(i));
        }
    }
    

打印结果

adh,aeh,afh,agh,adi,aei,afi,agi,
bdh,beh,bfh,bgh,bdi,bei,bfi,bgi,
cdh,ceh,cfh,cgh,cdi,cei,cfi,cgi,
**********************************************************
adh
bdh
cdh
aeh
beh
ceh
afh
bfh
cfh
agh
bgh
cgh
adi
bdi
cdi
aei
bei
cei
afi
bfi
cfi
agi
bgi
cgi

结语

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