Submission #48772317

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Source Code Expand

#include <bits/stdc++.h>
#include <atcoder/modint>

namespace {
    using ModInt [[maybe_unused]] = atcoder::modint998244353;
    using Num [[maybe_unused]] = long long int;
    using Vec [[maybe_unused]] = std::vector<Num>;
    using Set [[maybe_unused]] = std::set<Num>;
    using Mset [[maybe_unused]] = std::multiset<Num>;
    using Edges [[maybe_unused]] = std::vector<std::vector<Num>>;

    template<typename T>
    using Q [[maybe_unused]] = std::queue<T>;

    template<typename T>
    using PQ [[maybe_unused]] = std::priority_queue<T, std::vector<T>, std::greater<T>>;
}

void solve(std::istream& is, std::ostream& os) {
    Num n, k;
    is >> n >> k;

    Vec ss(n, 2);
    for(Num i{0}; i<k; ++i) {
        Num a;
        is >> a;
        --a;
        ss.at(a) -= 1;
    }

    Vec ts;
    for(Num i{0}; i<n; ++i) {
        for(Num j{0}; j<ss.at(i); ++j) {
            ts.push_back(i);
        }
    }

    Num size = static_cast<Num>(ts.size());
    if ((size % 2) == 0) {
        Num ans {0};
        for(Num i{0}; i<size; i+=2) {
            ans += std::abs(ts.at(i+1) - ts.at(i));
        }
        os << ans << "\n";
        return;
    }

    Vec cumsum_f {0};
    for(Num i{0}; (i+1)<size; i+=2) {
        Num d = std::abs(ts.at(i+1) - ts.at(i));
        cumsum_f.push_back(cumsum_f.back() + d);
    }

    Vec cumsum_b {0};
    for(Num i{size-2}; i>=1; i-=2) {
        Num d = std::abs(ts.at(i+1) - ts.at(i));
        cumsum_b.push_back(cumsum_b.back() + d);
    }

    Num ans {1000000000000000000LL};
    for(Num i{0}; i<size; ++i) {
        if ((i % 2) == 0) {
            Num d = cumsum_f.at(i / 2) + cumsum_b.at((size - i - 1) / 2);
            ans = std::min(ans, d);
        } else {
            Num d = cumsum_f.at(i / 2) + cumsum_b.at((size - i - 1) / 2) + std::abs(ts.at(i+1) - ts.at(i-1));
            ans = std::min(ans, d);
        }
    }

    os << ans << "\n";
}

int main(void) {
    solve(std::cin, std::cout);
    return 0;
}

Submission Info

Judge Result