Submission #143777

#	Time	Username	Problem	Language	Result	Execution time	Memory
143777		jwvg0425	Arranging Shoes (IOI19_shoes)	C++17	45 / 100	119 ms	20856 KiB

shoes

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

std::set<int> minus[100005];
std::set<int> plus[100005];

long long count_swaps(std::vector<int> s) {
    std::vector<bool> used(s.size(), false);

    long long ans = 0;
    long long useCount = 0;

    for (int i = 0; i < s.size(); i++)
    {
        if (s[i] > 0)
            plus[s[i]].insert(i);
        else
            minus[-s[i]].insert(i);
    }

    for (int i = 0; i < s.size(); i++)
    {
        if (used[i])
        {
            useCount--;
            continue;
        }

        if (s[i] > 0)
        {
            int near = *minus[s[i]].lower_bound(i);
            minus[s[i]].erase(near);
            used[near] = true;
            ans += near - i - useCount;
        }
        else
        {
            int near = *plus[-s[i]].lower_bound(i);
            plus[-s[i]].erase(near);
            used[near] = true;
            ans += near - i - 1 - useCount;
        }

        useCount++;
    }

    return ans;
}

Compilation message (stderr)

shoes.cpp: In function 'long long int count_swaps(std::vector<int>)':
shoes.cpp:13:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < s.size(); i++)
                     ~~^~~~~~~~~~
shoes.cpp:21:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < s.size(); i++)
                     ~~^~~~~~~~~~

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