Submission #59491355

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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>>;

    const std::vector<std::pair<Num, Num>> dyxs {{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
    std::map<char, std::pair<Num, Num>> directions {{'D', {1, 0}}, {'U', {-1, 0}}, {'R', {0, 1}}, {'L', {0, -1}}};

    template<typename T>
    void print_oneline(const std::vector<T>& vec, std::ostream& os) {
        const auto size = vec.size();
        for(size_t i{0}; i<size; ++i) {
            os << vec.at(i) << (((i+1) == size) ? '\n' : ' ');
        }
    }

    template<typename T>
    void print_each(const std::vector<T>& vec, std::ostream& os) {
        const auto size = vec.size();
        for(size_t i{0}; i<size; ++i) {
            os << vec.at(i) << '\n';
        }
    }
}

void solve(std::istream& is, std::ostream& os) {
    std::string s;
    is >> s;
    const Num n = s.size();

    if (n == 1) {
        os << "1\n";
        return;
    }

    if (n == 2) {
        if (s.at(0) == s.at(1)) {
            os << "2\n";
        } else {
            os << "1\n";
        }
        return;
    }

    char prev {'^'};
    Num len {0};
    Vec ls;
    s += '$';

    for(Num i{0}; i<=n; ++i) {
        const auto c = s.at(i);
        if (c == prev) {
            ++len;
        } else {
            if (len > 0) {
                ls.push_back(len);
            }
            len = 1;
        }
        prev = c;
    }

    if (ls.size() < 3) {
        os << *std::ranges::max_element(ls) << "\n";
        return;
    }

    Num ans {0};
    Num fwd {0};
    Num rev {0};
    const auto center = n / 2;
    const auto sz = ls.size();
    for(size_t i{0}; (i+1)<sz; ++i) {
        fwd += ls.at(i);
        rev += ls.at(sz-1-i);
        if (fwd <= center) {
            ans = std::max(ans, fwd);
        }
        if (rev <= center) {
            ans = std::max(ans, rev);
        }
    }

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

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

Submission Info

Judge Result