How to split a vector into n “almost equal” parts

Question

I have a problem that I would like to merge a large number of images using ImageMagick\'s convert.exe, but under Windows I have a 8192 byte long command line limit.

Answer 1

Here is my solution:

template
std::vector> SplitVector(const std::vector& vec, size_t n)
{
    std::vector> outVec;

    size_t length = vec.size() / n;
    size_t remain = vec.size() % n;

    size_t begin = 0;
    size_t end = 0;

    for (size_t i = 0; i < std::min(n, vec.size()); ++i)
    {
        end += (remain > 0) ? (length + !!(remain--)) : length;

        outVec.push_back(std::vector(vec.begin() + begin, vec.begin() + end));

        begin = end;
    }

    return outVec;
}