Submission #50536832

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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 ns(n);
    for(auto&& a : ns) {
        is >> a;
    }

    const auto left_min = *std::min_element(ns.begin(), ns.begin() + k);
    const auto right_max = *std::max_element(ns.begin() + k, ns.end());
    if (left_min >= right_max) {
        os << "-1\n";
        return;
    }

    if (ns.at(k-1) < ns.at(k)) {
        os << "1\n";
        return;
    }

    std::vector<std::pair<Num, Num>> ordered;
    for(Num i{0}; i<k; ++i) {
        ordered.push_back(std::make_pair(ns.at(i), -i));
    }

    for(Num i{k}; i<n; ++i) {
        ordered.push_back(std::make_pair(ns.at(i), -i));
    }

    std::ranges::sort(ordered);

    Set nodes;
    constexpr Num Inf = 1000000000000000LL;
    Num ans = Inf;
    for(Num i{0}; i<n; ++i) {
        const auto& [val, nidx] = ordered.at(i);
        const auto idx = -nidx;
        if (idx < k) {
            nodes.insert(idx);
        } else if (!nodes.empty()) {
            ans = std::min(ans, idx - (*nodes.rbegin()));
        }
    }

    if (ans >= Inf) {
        os << "-1\n";
    } else {
        os << ans << "\n";
    }
}

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

Submission Info

Judge Result