Submission #298321

#	Time	Username	Problem	Language	Result	Execution time	Memory
298321		emil_physmath	Arranging Shoes (IOI19_shoes)	C++17	10 / 100	1087 ms	20632 KiB

shoes

#include "shoes.h"
#include <bits/stdc++.h>
using namespace std;
using llong = long long;
#define BUGO(x) cerr << #x << " = " << x << '\n';
const int maxN = 200'005;

int t[maxN * 4];

int Get(int v, int vl, int vr, int i) {
    if (vl == vr)
        return t[v];
    int vm = vl + (vr - vl) / 2;
    if (i <= vm)
        return t[v] + Get(v * 2, vl, vm, i);
    return t[v] + Get(v * 2 + 1, vm + 1, vr, i);
}
void Add(int v, int vl, int vr, int l, int r, int val) {
    if (l > vr || vl > r) return;
    if (l <= vl && vr <= r) {
        t[v] += val;
        return;
    }
    int vm = vl + (vr - vl) / 2;
    Add(v * 2, vl, vm, l, r, val);
    Add(v * 2 + 1, vm + 1, vr, l, r, val);
}
vector<int> pos_[maxN * 2];
vector<int>* pos = pos_ + maxN;
long long count_swaps(vector<int> a) {
    auto A = [&a](int i) {
        int l = 0, r = a.size() - 1;
        int ans = -1;
        while (l <= r) {
            cerr << i << ": (" << l << ", " << r << ")\n";
            int m = (l + r) / 2;
            int cur = Get(1, 0, a.size() - 1, m);
            if (cur >= i) {
                ans = m;
                r = m - 1;
            }
            else
                l = m + 1;
        }
        if (ans == -1) {
            cerr << i << '\n';
            throw;
        }
        return ans;
    };
    int n = a.size();
    for (int i = 1; i < n; ++i)
        Add(1, 0, n - 1, i, i, i);
    for (int i = 0; i < n; ++i)
        pos[a[i]].push_back(i);
    for (int i = -n; i <= n; ++i)
        reverse(pos[i].begin(), pos[i].end());
    llong ans = 0;
    for (int i = 0; i < n; i += 2)
    {
        int ai = a[A(i)], ai1 = a[A(i + 1)];
        if (abs(ai) == abs(ai1) && ai < 0 && ai1 > 0) {
            pos[ai].pop_back();
            pos[ai1].pop_back();
            continue;
        }
        int j = pos[-ai].back();
        pos[-ai].pop_back();
        pos[ai].pop_back();

        ans += (Get(1, 0, n - 1, j) - (i + 1));
        if (i + 1 <= j - 1)
            Add(1, 0, n - 1, i + 1, j - 1, 1);
        // while (j > i + 1) {
            // ++ans;
            // swap(a[j - 1], a[j]);
            // --j;
        // }
        if (ai > 0) {
            // swap(a[i], a[i + 1]);
            ++ans;
        }
    }
    return ans;
}

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