java - JAVA组合生成器

Question

我正在尝试查找多个数组中项目的所有组合。数组的数量是随机的(可以是 2、3、4、5...)。每个数组中的元素数量也是随机的。

例如，我有 3 个数组:

String[][] array1 = {{"A1","A2","A3"},{"B1","B2","B3"},{"C1","C2"}};

我想生成一个包含所有可能组合的数组:

A1, B1, C1
A1, B1, C2
A1, B2, C1
A1, B2, C2
A1, B3, C1
A1, B3, C2
A2, B1, C1
A2, B1, C2 ...

Answer 1

您可以使用“类似计数器”的策略来创建组合，即将这些数组视为数字的数字，如下所示:

public static String[][] generateCombinations(String[]... arrays) {
    if (arrays.length == 0) {
        return new String[][]{{}};
    }
    int num = 1;
    for (int i = 0; i < arrays.length; i++) {
        num *= arrays[i].length;
    }

    String[][] result = new String[num][arrays.length];

    // array containing the indices of the Strings
    int[] combination = new int[arrays.length];

    for (int i = 0; i < num; i++) {
        String[] comb = result[i];
        // fill array
        for (int j = 0; j < arrays.length; j++) {
            comb[j] = arrays[j][combination[j]];
        }

        // generate next combination
        for (int j = arrays.length-1; j >= 0; j--) {
            int n = ++combination[j];
            if (n >= arrays[j].length) {
                // "digit" exceeded valid range -> back to 0 and continue incrementing
                combination[j] = 0;
            } else {
                // "digit" still in valid range -> stop
                break;
            }
        }
    }
    return result;
}

该方法的调用方式如下:

generateCombinations(
            new String[]{"A1","A2","A3"},
            new String[]{"B1","B2","B3"},
            new String[]{"C1","C2"}
       )

或者像这样:

generateCombinations(array1)