Submission #559890

#	Time	Username	Problem	Language	Result	Execution time	Memory
559890		cegax	Arranging Shoes (IOI19_shoes)	C++17	100 / 100	88 ms	15820 KiB

shoes

#include <bits/stdc++.h>
using namespace std;
#define all(c) (c).begin(), (c).end()
#define rall(A) A.rbegin(),A.rend()
#define pb push_back 
#define dbg(x) do {cerr << #x <<" = " << (x) << endl; } while (false)
typedef long long ll;
typedef pair<int, int> ii;
typedef vector<int> vi;
typedef vector<ii> vii;
//cout << setprecision(12) << fixed;

struct BIT {
    vector<int> bit;  // binary indexed tree
    int n;

    BIT(int n) {
        this->n = n;
        bit.assign(n, 0);
    }

    BIT(vector<int> a) : BIT(a.size()) {
        for (size_t i = 0; i < a.size(); i++)
            add(i, a[i]);
    }

    int sum(int r) {
        int ret = 0;
        for (; r >= 0; r = (r & (r + 1)) - 1)
            ret += bit[r];
        return ret;
    }

    int sum(int l, int r) {
        return sum(r) - sum(l - 1);
    }

    void add(int idx, int delta) {
        for (; idx < n; idx = idx | (idx + 1))
            bit[idx] += delta;
    }
};


ll count_swaps(vector<int> s) {
    int n = s.size() >> 1;
    vi L[n+1], R[n+1];

    for(int i = 0; i < 2 * n; i++) {
        cin >> s[i];

        if(s[i] < 0) 
            L[-s[i]].pb(i+1);
        else 
            R[s[i]].pb(i+1);
    }

    for(int i = 1; i <= n; i++) {
        reverse(all(L[i]));
        reverse(all(R[i]));
    }

    int a[2*n + 1];

    bool vis[2 * n + 1];
    memset(vis, 0, sizeof(vis));

    int ind = 1;
    for(int i = 0; i < 2 * n; i++) {
        if(vis[i]) continue;

        int l, r;

        l = L[abs(s[i])].back();
        r = R[abs(s[i])].back();

        vis[l-1] = vis[r-1] = 1;

        L[abs(s[i])].pop_back();
        R[abs(s[i])].pop_back();
        
        a[l] = ind++;
        a[r] = ind++;
    }

    ll ans = 0;

    BIT ft(2 * n + 2);

    for(int i = 1; i <= 2 * n; i++) {
        ans += ft.sum(a[i] + 1, 2 * n + 1);
        ft.add(a[i], 1);
    }

    return ans;
}

// int main() {
//     ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
//     int n; cin >> n;
//     vi s(2 * n);
//
//     for(int i = 0; i < 2 * n; i++)
//         cin >> s[i];
//
//     cout << count_swaps(s) << "\n";
//
//     return 0;
// }
//

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