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// g++ -Wall -Wextra -Wpedantic -std=c++17 cpp/ch-1.cpp
#include <algorithm> // transform
#include <iostream> // cout
#include <numeric> // accumulate
#include <sstream> // stringstream
#include <vector>
int fun(std::vector<int> const& ints) {
std::vector<int> out;
const std::size_t N = ints.size();
std::vector<std::size_t> indexes(N);
std::iota(indexes.begin(), indexes.end(), 1u);
std::transform(ints.cbegin(), ints.cend(),
indexes.cbegin(), std::back_inserter(out),
[&](const int& value, const std::size_t& index) {
return N % index == 0 ? value * value : 0; });
return std::accumulate(out.cbegin(), out.cend(), 0);
}
int main(void) {
// Tests
std::vector<std::pair<std::vector<int>, int>> tests = {
{{1, 2, 3, 4}, 21},
{{2, 7, 1, 19, 18, 3}, 63},
};
for (const auto& [input, expected_output] : tests) {
int got = fun(input);
if (got != expected_output) {
std::stringstream error_msg;
error_msg << "Expected " << expected_output << ", got " << got;
throw std::runtime_error(error_msg.str());
}
}
std::cout << "done-testing, success\n";
}
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