Submission #51377155

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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) {
    std::string s;
    is >> s;

    const Num size = s.size();
    std::map<char, Num> table;
    for(const auto& c : s) {
        table[c] += 1;
    }

    Num n_combi = (size * (size - 1)) / 2;
    Num n_sames {0};
    for(const auto& [k,v] : table) {
        n_sames += (v * (v-1)) / 2;
    }

    Num ans = n_combi - n_sames + (n_sames > 0);
    os << ans << "\n";
}

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

Submission Info

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