Submission #868395

#	Time	Username	Problem	Language	Result	Execution time	Memory
868395		toma_ariciu	Arranging Shoes (IOI19_shoes)	C++17	45 / 100	30 ms	11476 KiB

shoes

#include "shoes.h"
#include <algorithm>
#include <iostream>

using namespace std;

class FenwickTree {
private:
    int sz;
    vector <int> v;
    int lsb(int x) {
        return (x & (-x));
    }
public:
    FenwickTree(int n) {
        sz = n;
        v.resize(sz + 1);
    }
    void update(int poz) {
        for (int i = poz; i <= sz; i += lsb(i)) {
            v[i]++;
        }
    }
    int query(int poz) {
        int ans = 0;
        for (int i = poz; i; i -= lsb(i)) {
            ans += v[i];
        }
        return ans;
    }
};

int n;

long long computeInversions(vector <int> v) {
    long long inv = 0;
    FenwickTree aib(2 * n);
    for (int i = 2 * n - 1; i >= 0; i--) {
        inv += aib.query(v[i]);
        aib.update(v[i] + 1);
    }
    return inv;
}


long long count_swaps(vector<int> s) {
    n = (int) s.size() / 2;
    vector <int> v(2 * n), ord;
    vector <vector <int>> pos(n + 1, vector <int>());
    int p1 = 0;
    for (int i = 0; i < 2 * n; i++) {
        if (s[i] < 0) {
            v[i] = p1;
            p1 += 2;
            ord.push_back(-s[i]);
        }
    }
    for (int i = 2 * n - 1; i >= 0; i--) {
        if (s[i] > 0) {
            int x = s[i];
            pos[x].push_back(i);
        }
    }
    for (int i = 0; i < n; i++) {
        int x = ord[i];
        int poz = pos[x].back();
        pos[x].pop_back();
        v[poz] = 2 * i + 1;
    }
    return computeInversions(v);
}

• Subtask 1: 10 / 10
• Subtask 2: 0 / 20
• Subtask 3: 20 / 20
• Subtask 4: 15 / 15
• Subtask 5: 0 / 20
• Subtask 6: 0 / 15