Convert 1D Array Into 2D Array

To create the 2D array, you need to first check if the length of the original array is equal to m*n. If it’s not, return an empty array because you can’t form a 2D array with m rows and n columns. If it is, you can start forming your 2D array.

Here’s a python solution:

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class Solution:
    def construct2DArray(self, original, m, n):
        if len(original) != m * n:
            return []

        result = []
        for i in range(0, len(original), n):
            result.append(original[i:i+n])

        return result

This solution works by iterating through the original array with steps of size n, and in each step, it creates a sublist of size n and adds it to the result. The range function starts from 0 and goes till len(original) with steps of size n.

For each i, it extracts the sublist original[i:i+n] and adds it to the result. This is done until all elements of original are processed.

If the size of original is not equal to m*n, it means we can’t form a 2D array of size m by n using the elements of original, so we return an empty list in that case.

     For  m=2,n=2

     i      i/n         i%n        [ ][ ]

    0]      0/2       0%2          [0][0]
    1]      1/2       1%2          [0][1]
    2]      2/2       2%2          [1][0]
    3]      3/2       3%2          [1][1]

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class Solution:
    def construct2DArray(self, original, m, n):
        if len(original) != m * n:
            return []

        result = [[0]*n for _ in range(m)]
        for i in range(len(original)):
            result[i//n][i%n] = original[i]

        return result