#include <algorithm>
#include <iostream>
#include <vector>
 
std::size_t xor_sum(const std::vector<std::uint32_t>& v)
{
	std::size_t res = 0;
 
	for (std::size_t b = 0; b != 32; ++b) {
		const std::size_t count_0 =
		    std::count_if(v.begin(), v.end(),
		                  [b](std::uint32_t n) { return (n >> b) & 0x01; });
		const std::size_t count_1 = v.size() - count_0;
        res += count_0 * count_1 << b;
	}
	return res;
}
 
int main() {
    std::cout << xor_sum({3, 5, 7}); // 12 = 3^5 + 3^7 + 5^7
}

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