Submission #262018

#	Time	Username	Problem	Language	Result	Execution time	Memory
262018		tiberiu	Arranging Shoes (IOI19_shoes)	C++14	10 / 100	0 ms	256 KiB

shoes

#include "shoes.h"
#include <vector>

using namespace std;

const int MAX_N = 1e5 + 10;

int aib[MAX_N];

void update(int pos, int val) {
    pos++;

    while (pos > 0) {
        aib[pos] += val;
        pos -= (pos & -pos);
    }
}

int query(int pos) {
    pos++;

    int ans = 0;
    while (pos < MAX_N) {
        ans += aib[pos];
        pos += (pos & -pos);
    }
    return ans;
}

long long count_swaps(std::vector<int> s) {
    int n = s.size() / 2;
    vector<int>* f = new vector<int>[2 * n + 1]() + n;

    for (int i = 0; i < 2 * n; i++)
        f[s[i]].push_back(i);

    vector<int> p(2 * n);
    for (int i = 1; i <= n; i++) {
        int j = 0;
        while (j < f[i].size()) {
            p[f[i][j]] = f[-i][j];
            p[f[-i][j]] = f[i][j];
            j++;
        }
    }
    long long ans = 0;
    for (int i = 0; i < 2 * n; i++) {
        if (p[i] < i)
            continue;

        if (s[p[i]] < s[i])
            ans++;

        ans += (p[i] - i - 1) - (query(p[i] - 1) - query(i));
        update(p[i], +1);
    }

    return ans;
}

Compilation message (stderr)

shoes.cpp: In function 'long long int count_swaps(std::vector<int>)':
shoes.cpp:40:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         while (j < f[i].size()) {
                ~~^~~~~~~~~~~~~

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