7-106 3103 两倍关系

#include <algorithm>
#include <cstdint>
#include <iomanip>
#include <iostream>
#include <limits>
#include <numeric>
#include <string>
#include <unordered_map>
#include <utility>
#include <vector>

using i32 = std::int32_t;
using i64 = std::int64_t;
using u32 = std::uint32_t;
using u64 = std::uint64_t;
using pii = std::pair<i32, i32>;
using pll = std::pair<i64, i64>;
using vi = std::vector<i32>;
using vll = std::vector<i64>;
using vpii = std::vector<pii>;
using vpll = std::vector<pll>;

void solve();

int main()
{
    std::cin.tie(nullptr)->sync_with_stdio(false);
    solve();
}

void solve()
{
    i32 n;
    vi array;
    bool endl = false;
    while (std::cin >> n)
    {
        if (n == -1)
        {
            return;
        }
        if (n == 0)
        {
            if (endl)
            {
                std::cout << std::endl;
            }
            std::sort(array.begin(), array.end());
            i32 count{0};
            for (u32 i = 0; i < array.size(); ++i)
            {
                for (u32 j = i + 1; j < array.size(); ++j)
                {
                    if (array[i] * 2 == array[j])
                    {
                        ++count;
                    }
                }
            }
            std::cout << count;
            array.clear();
            endl = true;
        }
        array.emplace_back(n);
    }
}