'How to binary fill a 2D array with all possible column combinations? (c++) [closed]

I want to fill a 2D array that is initialized with 0's to a binary array that indicates all possible combinations of the columns. As input variable, I only have the number of alternatives. From this input, I calculate the possible combinations of the alternatives. Next, I create a 2D array with the number of rows equal to the number of possible combinations and with the number of columns equal to the number of alternatives that was given as input. I initialize all values of the 2D arrays with a 0. Now I try to transform this 2D array to an array with 0's and 1's, indicating all possible combinations of alternatives. Below I have attached a practical example that clarifies the goal of the code.

Can anyone help my with writing the for loops that can solve my problem? Thanks in advance!

Practical example

c++arrays


Solution 1:[1]

I think 0000 is one of the combinations, too.

You can find the patterns:

Each column repeats k 0s then k 1s where k = 2^(j+1).

E.g. 4 bits -> 2^4 combinations

int a[16][4] = {0};
for (int i = 0; i < 16; i++) {
    for (int j = 0; j < 4; j++) {
        int k = (int)pow(2, j+1);
        if (i % k + 1 > k / 2) {
            a[i][j] = 1;
        }
    }
}

Output:

0000
1000
0100
1100
0010
1010
0110
1110
0001
1001
0101
1101
0011
1011
0111
1111

Sources

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Source: Stack Overflow

Solution Source
Solution 1

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