Longest common prefix (Leetcode)
I'm only going to review the C++ code here, as all I could suggest for the Python code also applies to the C++, so is included in this review.
Firstly, the interface is quite limiting - the inputs need to be converted to vector of string-view objects, which is inconvenient if I have a linked-list of strings, or an input stream yielding QStrings.  I recommend changing to accept a pair of iterators, or in sufficiently modern C++, a std::ranges::range object.
This test is inefficient:
word.find(common, 0) != 0

If we don't find common at position 0, find() will continue searching the rest of the string (the Python code is better here).  We need an implementation of starts_with() (which is in C++20's std::string) - or better, we could use std::mismatch() to directly find how much of the strings are common, eliminating the loop where we repeatedly remove a single character.
Here's my attempt at that, also with a simple optimisation to return early when the common string becomes empty:
#include &lt;algorithm&gt;
#include &lt;iterator&gt;
#include &lt;string_view&gt;
#include &lt;vector&gt;

namespace
{
    template&lt;typename String&gt;
    String common_prefix(const String&amp; a, const String&amp; b)
    {
        using std::begin;
        using std::end;
        auto end_iter = std::mismatch(begin(a), end(a), begin(b), end(b));
        if (end_iter.first == end(a)) { return a; }
        if (end_iter.second == end(b)) { return b; }
        return String(begin(a), end_iter.first - begin(a));
    }
}

template&lt;typename Iter, typename IterEnd = Iter&gt;
std::string_view get_common_prefix(Iter first, IterEnd last)
{
    if (first==last) { return &quot;&quot;; }
    std::string_view common = *first;
    for (auto it = first;  it != last;  ++it) {
        common = common_prefix(common, *it);
        if (common.empty()) { return common; }
    }
    return common;
}

template&lt;typename Container&gt;
std::string_view get_common_prefix(const Container&amp; words)
{
    using std::begin;
    using std::end;
    return get_common_prefix(begin(words), end(words));
}