#1008432 (C++17) No.2873 Kendall's Tau

• 問題: No.2873 Kendall's Tau
• ユーザー: maeshun
• 提出日時: 2024-09-08 13:46:55
• 言語: C++17 (gcc 13.3.0 + boost 1.87.0)
• 結果: AC
• 実行時間: 497 ms / 4,500 ms
• コード長: 2,126 bytes
• コンパイル時間: 4,915 ms
• コンパイル使用メモリ: 269,220 KB
• 最終ジャッジ日時: 2025-02-24 05:36:34
• ジャッジサーバーID （参考情報）: judge4 / judge3

ファイルパターン	結果
sample	AC * 3
other	AC * 30

ソースコード

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
#define rep(i, n) for(ll i=0;i<(n);++i)
#define rep1(i, n) for(int i=1;i<=(n);i++)
#define ll long long
using mint = modint998244353;
using P = pair<ll,ll>;
using lb = long double;
using T = tuple<ll, ll, ll>;
#ifdef LOCAL
#  include <debug_print.hpp>
#  define dbg(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define dbg(...) (static_cast<void>(0))
#endif
// Coodinate Compression
// https://youtu.be/fR3W5IcBGLQ?t=8550
template<typename T=long long>
struct CC {
  bool initialized;
  vector<T> xs;
  CC(): initialized(false) {}
  void add(T x) { xs.push_back(x);}
  void init() {
    sort(xs.begin(), xs.end());
    xs.erase(unique(xs.begin(),xs.end()),xs.end());
    initialized = true;
  }
  int operator()(T x) {
    if (!initialized) init();
    return upper_bound(xs.begin(), xs.end(), x) - xs.begin() - 1;
  }
  T operator[](int i) {
    if (!initialized) init();
    return xs[i];
  }
  int size() {
    if (!initialized) init();
    return xs.size();
  }
};
int main()
{
    ll n;
    cin >> n;
    vector<pair<ll, ll>> vs(n);
    rep(i,n) cin >> vs[i].first >> vs[i].second;
    sort(vs.begin(),vs.end());
    CC cx, cy;
    rep(i,n) cy.add(vs[i].second);
    ll sy = cy.size();
    ll p = 0;
    ll q = 0;
    fenwick_tree<ll> bit(sy);
    for(ll i=0;i<n;) {
        ll j = i;
        vector<ll> y;
        while(j<n && vs[j].first==vs[i].first) {
            y.push_back(cy(vs[j].second));
            j++;
        }
        for(ll Y : y) {
            p += bit.sum(0, Y);    
            q += bit.sum(Y+1, sy);
        }  
        for(ll Y : y) {
            bit.add(Y,1);
        }
        i = j;
    }
    map<ll,ll> x, y;
    lb r = n * (n-1)/2;
    lb s = n * (n-1)/2;
    rep(i,n) x[vs[i].first]++;
    rep(i,n) y[vs[i].second]++;
    for(auto p : x) {
        r -= (ll)p.second*(p.second-1)/2;
    }
    for(auto p : y) {
        s -= (ll)p.second*(p.second-1)/2;
    }
    dbg(p,q,r,s);
    lb ans = (p-q) / sqrt(r*s);
    cout << fixed << setprecision(16) << ans << endl;
    return 0;
}
 
 
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX