Question

For given n inputs, I need to generate all possible input combinations using C++

eg. n =4

I need to get,

1010101010101010

1100110011001100

1111000011110000

1111111100000000

(EDIT : In case this is not clear, these are the input combinations read column-wise)

I need these to perform operations like & and | so it would be best if I get them in their integer representation as n different variables.

I tried doing it using bitset for 32 input combinations but it took a long time to process. I was hoping if you guys had any ideas on a better implementation?

EDIT : Example when n=3

10101010

11001100

11110000

Answer 1

Here is a short implementation that generates that output:

void print_mask(int n){
    for (int level = 0; level < n; level++){
        for (int i = (1<<n)-1; i>=0; i--)   // we'll always output 2**n bits
            printf("%d", (i >> level) & 1);
        printf("\n");
    };
};