cpp_prac/junk/4.cc

#include <iostream>
#include <ranges>
#include <vector>

template <typename InputIt, typename OutputIt, typename Pred>
std::pair<InputIt, OutputIt> copy_while(InputIt first, InputIt last,
                                        OutputIt out, Pred p);

std::vector<int> take_while_sum_less_than(std::vector<int> &v, int n) {
    std::vector<int> out;
    int acc = 0;
    while (true) {
        if (v.back() + acc > n) {
            int next = v.back();
            out.push_back(n);
            v.pop_back();
        }
    }
}

#if __cplusplus > 202002L
// #include <ranges>
// #include <numeric>

std::vector<int> take_while_sum_less_than(const std::vector<int> &v, int n) {
    int sum = 0;

    auto result = v | std::ranges::views::take_while([&sum, n](int x) {
                      if (sum + x < n) {
                          sum += x;
                          return true;
                      }
                      return false;
                  });

    return std::vector<int>(result.begin(), result.end());
}
#endif