How do I solve this array problem in C language?

Question

I have 2 arrays: int element[3] = {0, 1, 2}; int quantity[3] = {2, 3, 4}; Now I want a result array that will have two zeros, three ones and four twos. int result[2+3+4] = {0, 0, 1, 1, 1, 2, 2, 2, 2}; How do I do this using loop?

Answer 1

You need to count the number of elements in the result array and to declare either a variable length array with the calculated value or to allocate dynamically such an array.

For example

int quantity[3] = {2, 3, 4};

size_t n = 0;
for ( size_t i = 0; i < 3; i++ )
{
    n += quantity[i];
}

int result[n];

// or
// int *result = malloc( n * sizeof( int ) );

And then in nested loops you need fill the resulted array.

For example

for ( size_t i = 0, j = 0; i < 3; i++ )
{
    for ( size_t k = 0; k < quantity[i]; k++ )
    {
        result[j++] = element[i];
    }
}