結果

問題 No.1282 Display Elements
ユーザー tkmst201
提出日時 2021-02-22 11:59:23
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 72 ms / 2,000 ms
コード長 2,536 bytes
コンパイル時間 2,206 ms
コンパイル使用メモリ 203,284 KB
最終ジャッジ日時 2025-01-19 03:24:46
ジャッジサーバーID
（参考情報） 		judge2 / judge5
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ファイルパターン 結果
other AC * 24
権限があれば一括ダウンロードができます
コンパイルメッセージ
main.cpp: In function ‘int main()’:
main.cpp:74:24: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
   74 |         REP(i, N) scanf("%d", &A[i]);
      |                   ~~~~~^~~~~~~~~~~~~
main.cpp:75:24: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
   75 |         REP(i, N) scanf("%d", &B[i]);
      |                   ~~~~~^~~~~~~~~~~~~

ソースコード

diff #
プレゼンテーションモードにする

#include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) begin(v),end(v)
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
using ll = long long;
using pii = pair<int, int>;
constexpr ll INF = 1ll<<30;
constexpr ll longINF = 1ll<<60;
constexpr ll MOD = 1000000007;
constexpr bool debug = false;
//---------------------------------//
/**
 * @brief https://tkmst201.github.io/Library/DataStructure/BinaryIndexedTree.hpp
 */
template<typename T>
struct BinaryIndexedTree {
    using value_type = T;
    using const_reference = const value_type &;
    using F = std::function<value_type (const_reference, const_reference)>;
    using size_type = std::size_t;
    
private:
    size_type n;
    F f;
    value_type id_elem;
    std::vector<value_type> node;
    
public:
    BinaryIndexedTree(size_type n, const F & f, const_reference id_elem)
        : n(n), f(f), id_elem(id_elem), node(n + 1, id_elem) {}
    
    size_type size() const noexcept {
        return n;
    }
    
    void add(size_type i, const_reference x) {
        assert(i < size());
        ++i;
        for (; i <= size(); i += i & -i) node[i] = f(node[i], x);
    }
    
    value_type sum(size_type i) const {
        assert(i <= size());
        value_type res = id_elem;
        for (; i > 0; i -= i & -i) res = f(node[i], res);
        return res;
    }
    
    size_type lower_bound(const_reference x) const {
        size_type res = 0;
        size_type s = id_elem, w = 1;
        while (w < size()) w <<= 1;
        for (; w > 0; w >>= 1) {
            if (res + w <= size()) {
                value_type cur = f(s, node[res + w]);
                if (cur < x) {
                    res += w;
                    s = cur;
                }
            }
        }
        return res;
    }
};
int main() {
    int N;
    cin >> N;
    vector<int> A(N), B(N);
    REP(i, N) scanf("%d", &A[i]);
    REP(i, N) scanf("%d", &B[i]);
    sort(ALL(A));
    
    auto compress = [](auto &&v, auto &&cv) -> void {
        for (auto &&u : v) cv.emplace_back(u);
        cv.emplace_back(INF);
        cv.emplace_back(-INF);
        std::sort(std::begin(cv), std::end(cv));
        cv.erase(std::unique(std::begin(cv), std::end(cv)), std::end(cv));
        for (auto &&u : v) u = std::lower_bound(std::begin(cv), std::end(cv), u) - std::begin(cv);
    };
    vector<int> cx;
    compress(B, cx);
    
    BinaryIndexedTree<int> bit(cx.size(), [](int x, int y) { return x + y; }, 0);
    ll ans = 0;
    REP(i, N) {
        bit.add(B[i], 1);
        ans += bit.sum(lower_bound(ALL(cx), A[i]) - cx.begin());
    }
    cout << ans << endl;
}
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