Submission #1073210

#	Time	Username	Problem	Language	Result	Execution time	Memory
1073210		andrei_iorgulescu	Arranging Shoes (IOI19_shoes)	C++14	100 / 100	38 ms	17244 KiB

shoes

#include <bits/stdc++.h>
#include "shoes.h"
#warning That's not FB, that's not FB

using namespace std;

using ll = long long;

ll n;
ll a[200005];
vector<int> p[100005], neg[100005];
int per[200005];
int aib[200005];

void update(int pos, int val)
{
    for (int i = pos; i <= 2 * n; i += (i & -i))
        aib[i] += val;
}

int query(int pos)
{
    int rr = 0;
    for (int i = pos; i > 0; i -= (i & -i))
        rr += aib[i];
    return rr;
}

ll count_swaps(vector<int> S)
{
    n = S.size() / 2;
    for (int i = 1; i <= 2 * n; i++)
        a[i] = S[i - 1];
    for (int i = 1; i <= 2 * n; i++)
    {
        if (a[i] > 0)
            p[a[i]].push_back(i);
        else
            neg[-a[i]].push_back(i);
    }
    ll ans = 0;
    for (int i = 1; i <= n; i++)
    {
        for (int j = 0; j < p[i].size(); j++)
        {
            if (p[i][j] < neg[i][j])
                ans++, swap(p[i][j], neg[i][j]);
            per[neg[i][j]] = p[i][j];
        }
    }
    for (int i = 1; i <= 2 * n; i++)
        update(i, 1);
    for (int i = 1; i <= 2 * n; i++)
    {
        if (per[i] == 0)
            continue;
        ans += query(per[i] - 1) - query(i);
        update(per[i], -1);
    }
    return ans;
}

Compilation message (stderr)

shoes.cpp:3:2: warning: #warning That's not FB, that's not FB [-Wcpp]
    3 | #warning That's not FB, that's not FB
      |  ^~~~~~~
shoes.cpp: In function 'll count_swaps(std::vector<int>)':
shoes.cpp:44:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   44 |         for (int j = 0; j < p[i].size(); j++)
      |                         ~~^~~~~~~~~~~~~

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