#559402 (C++17) No.1115 二つの数列 / Two Sequences

• 問題: No.1115 二つの数列 / Two Sequences
• ユーザー: y
• 提出日時: 2020-09-27 07:04:09
• 言語: C++17 (gcc 13.3.0 + boost 1.87.0)
• 結果: AC
• 実行時間: 84 ms / 2,000 ms
• コード長: 6,687 bytes
• コンパイル時間: 1,884 ms
• コンパイル使用メモリ: 198,752 KB
• 最終ジャッジ日時: 2025-01-14 22:43:33
• ジャッジサーバーID （参考情報）: judge4 / judge4

ファイルパターン	結果
sample	AC * 5
other	AC * 35

ソースコード

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#include <bits/stdc++.h>
using namespace std;
// #define LOCAL // 提出時はコメントアウト
#define DEBUG_
typedef long long ll;
const double EPS = 1e-9;
const ll INF = ((1LL<<62)-(1LL<<31));
typedef vector<ll> vecl;
typedef pair<ll, ll> pairl;
template<typename T, typename U> using mapv = map<T,vector<U>>;
#define ALL(v) v.begin(), v.end()
#define REP(i, x, n) for(int i = x; i < n; i++)
#define rep(i, n) REP(i, 0, n)
#define contains(S,x) find(ALL(S),x) != S.end()
ll llceil(ll a,ll b) { return (a+b-1)/b; }
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
template<class T> vector<vector<T>> genarr(ll n, ll m, T init) { return vector<vector<T>>(n,vector<T>(m,init)); }
///// DEBUG
#define DUMPOUT cerr
#define repi(itr, ds) for (auto itr = ds.begin(); itr != ds.end(); itr++)
template<typename T>istream&operator>>(istream&is,vector<T>&vec){for(T&x:vec)is>>x;return is;}
template<typename T,typename U>ostream&operator<<(ostream&os,pair<T,U>&pair_var){os<<"("<<pair_var.first<<", "<<pair_var.second<<")";return os;}
template<typename T>ostream&operator<<(ostream&os,const vector<T>&vec){os<<"{";for(int i=0;i<vec.size();i++){os<<vec[i]<<(i+1==vec.size()?"":", ");}
os<<"}";return os;}
template<typename T,typename U>ostream&operator<<(ostream&os,map<T,U>&map_var){os<<"{";repi(itr,map_var){os<<*itr;itr++;if(itr!=map_var.end())os<<", 
    ";itr--;}
os<<"}";return os;}
template<typename T>ostream&operator<<(ostream&os,set<T>&set_var){os<<"{";repi(itr,set_var){os<<*itr;itr++;if(itr!=set_var.end())os<<", ";itr--;}
os<<"}";return os;}
void dump_func(){DUMPOUT<<endl;}
template<class Head,class...Tail>void dump_func(Head&&head,Tail&&...tail){DUMPOUT<<head;if(sizeof...(Tail)>0){DUMPOUT<<", ";}
dump_func(std::move(tail)...);}
#ifndef LOCAL
#undef DEBUG_
#endif
#ifdef DEBUG_
#define DEB
#define dump(...)                                                          \
DUMPOUT << "  " << string(#__VA_ARGS__) << ": "                            \
        << "[" << to_string(__LINE__) << ":" << __FUNCTION__ << "]"        \
        << endl                                                            \
        << "    ",                                                         \
    dump_func(__VA_ARGS__)
#else
#define DEB if (false)
#define dump(...)
#endif
//////////
// SegTree: https://atcoder.github.io/ac-library/document_ja/segtree.html
// @param n `0 <= n`
// @return minimum non-negative `x` s.t. `n <= 2**x`
int ceil_pow2(int n) {
    int x = 0;
    while ((1U << x) < (unsigned int)(n)) x++;
    return x;
}
// @param n `1 <= n`
// @return minimum non-negative `x` s.t. `(n & (1 << x)) != 0`
int bsf(unsigned int n) {
#ifdef _MSC_VER
    unsigned long index;
    _BitScanForward(&index, n);
    return index;
#else
    return __builtin_ctz(n);
#endif
}
template <class S, S (*op)(S, S), S (*e)()> struct segtree {
  public:
    segtree() : segtree(0) {}
    segtree(int n) : segtree(std::vector<S>(n, e())) {}
    segtree(const std::vector<S>& v) : _n(int(v.size())) {
        log = ceil_pow2(_n);
        size = 1 << log;
        d = std::vector<S>(2 * size, e());
        for (int i = 0; i < _n; i++) d[size + i] = v[i];
        for (int i = size - 1; i >= 1; i--) {
            update(i);
        }
    }
    void set(int p, S x) { // O(logn)
        assert(0 <= p && p < _n);
        p += size;
        d[p] = x;
        for (int i = 1; i <= log; i++) update(p >> i);
    }
    S get(int p) { // O(1)
        assert(0 <= p && p < _n);
        return d[p + size];
    }
    S prod(int l, int r) { // [l,r): O(logn)
        assert(0 <= l && l <= r && r <= _n);
        S sml = e(), smr = e();
        l += size;
        r += size;
        while (l < r) {
            if (l & 1) sml = op(sml, d[l++]);
            if (r & 1) smr = op(d[--r], smr);
            l >>= 1;
            r >>= 1;
        }
        return op(sml, smr);
    }
    S all_prod() { return d[1]; } // [0,n)
    template <bool (*f)(S)> int max_right(int l) { // segtree上で二分探索 O(logn)
        return max_right(l, [](S x) { return f(x); });
    }
    template <class F> int max_right(int l, F f) { // segtree上で二分探索 O(logn)
        assert(0 <= l && l <= _n);
        assert(f(e()));
        if (l == _n) return _n;
        l += size;
        S sm = e();
        do {
            while (l % 2 == 0) l >>= 1;
            if (!f(op(sm, d[l]))) {
                while (l < size) {
                    l = (2 * l);
                    if (f(op(sm, d[l]))) {
                        sm = op(sm, d[l]);
                        l++;
                    }
                }
                return l - size;
            }
            sm = op(sm, d[l]);
            l++;
        } while ((l & -l) != l);
        return _n;
    }
    template <bool (*f)(S)> int min_left(int r) { // segtree上で二分探索 O(logn)
        return min_left(r, [](S x) { return f(x); });
    }
    template <class F> int min_left(int r, F f) { // segtree上で二分探索 O(logn)
        assert(0 <= r && r <= _n);
        assert(f(e()));
        if (r == 0) return 0;
        r += size;
        S sm = e();
        do {
            r--;
            while (r > 1 && (r % 2)) r >>= 1;
            if (!f(op(d[r], sm))) {
                while (r < size) {
                    r = (2 * r + 1);
                    if (f(op(d[r], sm))) {
                        sm = op(d[r], sm);
                        r--;
                    }
                }
                return r + 1 - size;
            }
            sm = op(d[r], sm);
        } while ((r & -r) != r);
        return 0;
    }
  private:
    int _n, size, log;
    std::vector<S> d;
    void update(int k) { d[k] = op(d[2 * k], d[2 * k + 1]); }
};
// (S,*): 結合律の成立と単位元の存在を満たせばOK
// 交換律は必要ないので演算の向きを恣意的に決めてOK
struct S {
    ll a;
    ll size;
};
S op(S l, S r) { return {l.a+r.a,l.size+r.size}; } // S * S
S e() { return {0,0}; } // モノイド·の単位元
int main() {
    #ifdef LOCAL
    ifstream in("../../Atcoder/input.txt");
    cin.rdbuf(in.rdbuf());
    #endif
    ll N;
    cin>>N;
    vecl A(N),B(N);
    rep(i,N) {
        cin>>A[i];
        A[i]--;
    }
    vecl X(N);
    rep(i,N) {
        cin>>B[i];
        X[--B[i]] = i;
    }
    ll invans = 0;
    segtree<S, op, e> seg(N);
    rep(i,N) {
        A[i] = X[A[i]];
        seg.set(A[i],{1,1});
        invans += seg.prod(0,A[i]).a;
    }
    ll ans = N * (N-1) / 2 - invans;
    cout << ans << endl;
    return 0;
}
 
 
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