Submission #971801

#	Time	Username	Problem	Language	Result	Execution time	Memory
971801		opPO	Arranging Shoes (IOI19_shoes)	C++14	100 / 100	181 ms	32448 KiB

shoes

#include "shoes.h"
#include <bits/stdc++.h>

#define sz(x) (int)x.size()

using namespace std;

struct fenwick {
    int n;
    vector<int> t;

    fenwick (int n) {
        this->n = n;
        t.resize(n);
    }

    void upd(int i, int x) {
        while (i < n) {
            t[i] += x;
            i |= i + 1;
        }
    }

    void upd(int l, int r, int x) {
        upd(l, x);
        upd(r + 1, -x);
    }

    int get(int i) {
        int r = 0;
        for (; i >= 0; i = (i & (i + 1)) - 1) {
            r += t[i];
        }
        return r;
    }
};

long long count_swaps(vector<int> s) {
    int n = sz(s) / 2;
    long long swaps = 0;
    set<int> unused;
    vector<set<int>> pos(2 * n + 2);
    for (int i = 0; i < 2 * n; i++) {
        unused.insert(i);
        pos[s[i] + n].insert(i);
    }

    fenwick f(2 * n + 2);
    for (int i = 0; i < n; i++) {
        int ft = *unused.begin();
        unused.erase(unused.begin());
        pos[s[ft] + n].erase(ft);
        int sc = *pos[-s[ft] + n].begin();
        pos[-s[ft] + n].erase(pos[-s[ft] + n].begin());
        unused.erase(sc);

        int actual_ft = ft + f.get(ft);
        int actual_sc = sc + f.get(sc);

        if (s[ft] < 0) {
            swaps += actual_sc - actual_ft - 1;
            f.upd(ft + 1, sc, +1);
        } else {
            swaps += actual_sc - actual_ft;
            f.upd(ft, sc, +1);
        }
    }

    return swaps;
}

/*
g++ -std=gnu++14 -O2 -Wall -pipe -static -o "shoes" "grader.cpp" "shoes.cpp"
*/

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