Submission #938959

#	Time	Username	Problem	Language	Result	Execution time	Memory
938959		riariti	Modsum (NOI12_modsum)	C++17	25 / 25	1 ms	604 KiB

modsum

#line 1 "MODSUM.cpp"
#include <bits/stdc++.h>

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);

    int n;
    std::cin >> n;
    std::vector<int> v(n), w(n);
    for (int i = 0; i < 2 * n; i++) {
        auto k = i / 2;
        std::cin >> (i % 2 ? w[k] : v[k]);
    }

    constexpr int K = 5;

    std::array<int, K> cnt{};
    // sum of 0 is 1
    cnt[0] = 1;

    for (int i = 0; i < n; i++) {
        std::array<int, 5> cur{};

        for (int j = v[i]; j <= w[i]; j++) {
            for (int k = 0; k < K; k++) {
                // basically what values if we add from before
                // i.e 1 2 3, then 2 3
                // 1 2
                // 1 3
                // 2 2
                // 2 3
                // 3 2
                // 3 3
                // => i.e j = 1 and if we change the variable to one of the mod
                // 5s then we see the sum changes and thus also we have to add
                // the cnt of that (number of values of that mod 5)
                cur[(j + k) % K] += cnt[k];
            }
        }

        std::swap(cnt, cur);
    }

    std::int64_t ans = 0;
    for (int i = 0; i < 5; i++) {
        std::int64_t v = std::pow(i, 4) + 2 * std::pow(i, 2);
        ans += cnt[i] * (v % 5 + 1);
    }

    std::cout << ans << "\n";

    return 0;
}

• Subtask 1: 5 / 5
• Subtask 2: 5 / 5
• Subtask 3: 5 / 5
• Subtask 4: 5 / 5
• Subtask 5: 5 / 5