Submission #298339

#	Time	Username	Problem	Language	Result	Execution time	Memory
298339		emil_physmath	Arranging Shoes (IOI19_shoes)	C++17	100 / 100	324 ms	29596 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) {
    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;
    set<int> s;
    for (int i = 0; i < n; ++i)
        s.insert(i);
    for (int i = 0; i < n; i += 2)
    {
        int ai = a[*s.begin()];
        int ai1 = a[*next(s.begin())];
        if (ai == -ai1 && ai < 0) {
            s.erase(s.begin(), next(s.begin(), 2));
            pos[ai].pop_back();
            pos[ai1].pop_back();
            continue;
        }
        int j = pos[-ai].back();
        s.erase(s.begin());
        s.erase(s.find(j));
        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, 0, j - 1, 1);
        if (ai > 0)
            ++ans;
    }
    return ans;
}

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