Submission #826774

#	Time	Username	Problem	Language	Result	Execution time	Memory
826774		kevinsogo	Arranging Shoes (IOI19_shoes)	C++17	100 / 100	715 ms	34264 KiB

shoes

#include <bits/stdc++.h>
using namespace std;
#include "shoes.h"
using ll = long long;

struct Seg {
    int i, j;
    int s = 0;
    Seg *l, *r;
    Seg(int i, int j): i(i), j(j) {
        if (j - i == 1) {
            l = r = nullptr;
        } else {
            int k = i + j >> 1;
            l = new Seg(i, k);
            r = new Seg(k, j);
        }
    }
    void inc(int I) {
        if (i <= I and I < j) {
            s++;
            if (l) l->inc(I), r->inc(I);
        }
    }
    int sum(int I) {
        return j <= I ? s : I <= i ? 0 : l->sum(I) + r->sum(I);
    }
};

ll count_swaps(vector<int> _seq) {
    vector<int> found(_seq.size() * 2 + 5);
    vector<ll> seq;
    for (int v : _seq) seq.push_back(ll(v) * _seq.size() + ((v > 0) - (v < 0)) * found[v + _seq.size()]++);
    unordered_map<ll,int> pos; pos.max_load_factor(0.5);
    for (int i = 0; i < seq.size(); i++) pos[seq[i]] = i;
    sort(seq.rbegin(), seq.rend(), [&](ll i, ll j) {
        int d = min(pos[i], pos[-i]) - min(pos[j], pos[-j]);
        return d ? d < 0 : i < j;
    });
    for (ll& v : seq) v = pos[v];
    ll ans = 0;
    Seg s(0, seq.size());
    for (ll v : seq) ans += s.sum(v), s.inc(v);
    return ans;
}

Compilation message (stderr)

shoes.cpp: In constructor 'Seg::Seg(int, int)':
shoes.cpp:14:23: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   14 |             int k = i + j >> 1;
      |                     ~~^~~
shoes.cpp: In function 'll count_swaps(std::vector<int>)':
shoes.cpp:35:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   35 |     for (int i = 0; i < seq.size(); i++) pos[seq[i]] = i;
      |                     ~~^~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 20 / 20
• Subtask 3: 20 / 20
• Subtask 4: 15 / 15
• Subtask 5: 20 / 20
• Subtask 6: 15 / 15