Submission #64829

#	Time	Username	Problem	Language	Result	Execution time	Memory
64829		Kubalionzzale	Sorting (IOI15_sorting)	C++14	0 / 100	4 ms	512 KiB

sorting

#include "sorting.h"

#include <iostream>
#include <algorithm>
#include <set>

std::set<int> notPlaced;

bool check(int n, int a[], int cur, int x[], int y[])
{
    notPlaced.clear();
    for (int i = cur; i >= 0; --i)
    {
        std::swap(a[x[i]], a[y[i]]);
    }

    for (int i = 0; i < n; ++i)
    {
        if (a[i] != i)
            notPlaced.insert(i);
    }

    for (int i = 0; i <= cur; ++i)
    {
        int one = x[i];
        int two = y[i];

        if (one != two)
        {
            if (a[one] == one)
                notPlaced.insert(one);
            if (a[two] == two)
                notPlaced.insert(two);

            std::swap(a[one], a[two]);
            if (a[one] == one)
                notPlaced.erase(one);
            if (a[two] == two)
                notPlaced.erase(two);
        }

        if (notPlaced.size() > 0)
        {
            int first = *(notPlaced.begin());
            int second = a[first];

            std::swap(a[first], a[second]);
            if (a[first] == first)
                notPlaced.erase(first);
            if (a[second] == second)
                notPlaced.erase(second);
        }
        else
        {
            continue;
        }
    }

    if (notPlaced.size() == 0)
        return 1;
    else
        return 0;
}

int findSwapPairs(int n, int a[], int m, int x[], int y[], int xans[], int yans[]) {

    int lowest = m;
    int l = 0, r = m - 1;
    while (l <= r)
    {
        int mid = l + (r - l) / 2;

        if (check(n, a, mid, x, y))
        {
            lowest = std::min(lowest, mid);

            r = mid - 1;
        }
        else
        {
            l = mid + 1;
        }
    }
    notPlaced.clear();

    for (int i = lowest; i >= 0; --i)
    {
        std::swap(a[x[i]], a[y[i]]);
    }

    for (int i = 0; i < n; ++i)
    {
        if (a[i] != i)
            notPlaced.insert(i);
    }

    for (int i = 0; i <= lowest; ++i)
    {
        int one = x[i];
        int two = y[i];

        if (one != two)
        {
            if (a[one] == one)
                notPlaced.insert(one);
            if (a[two] == two)
                notPlaced.insert(two);

            std::swap(a[one], a[two]);
            if (a[one] == one)
                notPlaced.erase(one);
            if (a[two] == two)
                notPlaced.erase(two);
        }

        if (notPlaced.size() > 0)
        {
            int first = *(notPlaced.begin());
            int second = a[first];

            xans[i] = first;
            yans[i] = second;
            std::swap(a[first], a[second]);
            if (a[first] == first)
                notPlaced.erase(first);
            if (a[second] == second)
                notPlaced.erase(second);
        }
        else
        {
            xans[i] = 0;
            yans[i] = 0;
        }
    }

    return lowest + 1;
}

• Subtask 1: 0 / 8
• Subtask 2: 0 / 12
• Subtask 3: 0 / 16
• Subtask 4: 0 / 18
• Subtask 5: 0 / 20
• Subtask 6: 0 / 26