用Java展平2d或3d数组

Question

I need to take a multidimensional array and flatten it so that if the array looks like:

[1,2,3]
[4,5,6]

Then it is transformed to:

[1,2,3,4,5,6]

I also need to accommodate 3D arrays and flatten them also.

Here is what I've got so far...

class ArrayOperations {
private int[] postFlattenedArray;

public ArrayOperations {

flattenedArray = new int[arrayDimensions[0]];
// arrayDimesnsions of 3,4 is a a 3x4 array; 3,4,5 is a 3x4x5 array

//set up ints to hold total size and dimensionality of array
int prod = 1
int dimensions = 0;

newArray = new int[prod - 1];

for (int i: arrayDimensions) {
  prod = prod * i;
  dimensions += 1;
  }
int k = 0;

for ( int i: arrayDimensions ){
for ( int j = 0; j <= i; j++ ){
  newArray[k++] = flattenedArray[j][0][0]
}
}

}

I know I need to run some nested for loops, but I'm having difficulty grasping how I would do this for different array dimensions. So if the array has dimensions; 3,5,6 then I am not sure how to run a loop so that it iterates like:

[1..4][0][0], [0][1..5][0], [0][0][1..6]

Answer 1

似乎最简单的解决方案是实现递归函数flatten （可能必须通用才能处理任何数组），如果已经平坦或在所有内部数组上递归调用自身，则它将返回数组本身。连接结果。

Answer 2

Try this.

static void flatten(Object object, List<Integer> list) {
    if (object.getClass().isArray()) 
        for (int i = 0; i < Array.getLength(object); ++i)
            flatten(Array.get(object, i), list);
    else
        list.add((int)object);
}

static int[] flatten(Object object) {
    List<Integer> list = new ArrayList<>();
    flatten(object, list);
    int size = list.size();
    int[] result = new int[size];
    for (int i = 0; i < size; ++i)
        result[i] = list.get(i);
    return result;
}

and

int[][][] array = {
    {{1, 2, 3}, {4, 5}},
    {{6}, {7, 8, 9}},
};
System.out.println(Arrays.toString(flatten(array)));
// -> [1, 2, 3, 4, 5, 6, 7, 8, 9]