Submission #1020336

#	Time	Username	Problem	Language	Result	Execution time	Memory
1020336		abdelhakim	Arranging Shoes (IOI19_shoes)	C++14	65 / 100	259 ms	38664 KiB

shoes

#include <bits/stdc++.h>
#define mod 1000000007LL
#define inf 1e17
#define ll long long
using namespace std;

void printvec(vector<int> vec)
{
    for (auto &&e : vec)
    {
        cout << e << ' ';
    }
    cout << endl;
}
ll maxn = 2e5 + 3;
vector<ll> tree(4*maxn);
ll query(ll node, ll x, ll y, ll l, ll r)
{
    if(max(l,x) > min(r, y))
    {
        return 0;
    }
    if(x <= l && r <= y)
    {
        return tree[node];
    }
    ll mid = (l+r)/2;
    return query(node*2, x, y, l, mid) + query(node*2+1,x, y, mid+1, r);
}

void update(ll node, ll l, ll r, ll index, ll val)
{
    if(index < l || index > r)
    {
        return;
    }
    if(l == r)
    {
        tree[node] = val;
        return;
    }
    ll mid = (l+r)/2;
    update(node*2, l, mid, index, val);
    update(node*2+1, mid+1, r, index, val);
    tree[node] = tree[node*2] + tree[node*2 + 1];
}
ll count_swaps(vector<int> s)
{
    ll n = s.size() / 2;
    bool sametype = true;
    for (int i = 1; i < n; i++)
    {
        if(abs(s[i])!=abs(s[i-1]))
        {
            sametype = false;
            break;
        }
    }
    if(n == 1) return s[0] > s[1];
    else if(n <= 8)
    {
            ll ans = inf;
    vector<pair<ll, ll>> perm;
    for (int i = 0; i < 2 * n; i++)
    {
        if (s[i] > 0)
        {
            perm.push_back({-s[i], s[i]});
        }
    }
    
    sort(perm.begin(), perm.end());
    vector<int> temp = s;
    do
    {
        s = temp;
        ll subans = 0;
        vector<int> v;
        for (int i = 0; i < n; i++)
        {
            v.push_back(perm[i].first);
            v.push_back(perm[i].second);
        }
        map<ll,vector<ll>> index;
        for (int i = 0; i < 2*n; i++)
        {
            index[v[i]].push_back(i);
        }
        vector<pair<ll,ll>> arr;
        for (int i = 0; i < 2*n; i++)
        {
            arr.push_back({s[i],index[s[i]][0]});
            index[s[i]].erase(index[s[i]].begin());
        }
        for (int i = 1; i < 2*n; i++)
        {
            for (int j = 0; j < i; j++)
            {
                if(arr[j].second > arr[i].second)subans++;
            }
        }
        ans = min(ans, subans);
    } while (next_permutation(perm.begin(), perm.end()));
    return ans;
    }
    else
    {
        ll ans = inf;
        ll subans = 0;
        vector<int> v;
        for (int i = 0; i < 2*n; i++)
        {
            if(s[i] > 0)
            {
                v.push_back(-s[i]);
                v.push_back(s[i]);
            }
        }
        map<ll,set<ll>> index;
        for (int i = 0; i < 2*n; i++)
        {
            index[v[i]].insert(i);
        }
        vector<int> arr;
        for (int i = 0; i < 2*n; i++) 
        {
            arr.push_back(*(index[s[i]].begin()));
            index[s[i]].erase(index[s[i]].begin()); // here
        }
        // printvec(arr);
        for (int i = 2*n-1; i >= 0; i--)
        {
            ll ac = query(1,0,arr[i],0,2*n-1);
            subans += ac;
            update(1,0,2*n-1,arr[i],1);
        }
        ans = min(ans, subans);
    // } while (next_permutation(perm.begin(), perm.end()));
    return ans;
    }

}

// int main()
// {
//     cout << count_swaps({-2, 2, 2, -2, -2, 2}) << endl;
// }

Compilation message (stderr)

shoes.cpp: In function 'long long int count_swaps(std::vector<int>)':
shoes.cpp:50:10: warning: variable 'sametype' set but not used [-Wunused-but-set-variable]
   50 |     bool sametype = true;
      |          ^~~~~~~~

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