Submission #1077779

#	Time	Username	Problem	Language	Result	Execution time	Memory
1077779		Ignut	Arranging Shoes (IOI19_shoes)	C++17	100 / 100	77 ms	17092 KiB

shoes

// Ignut

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

const int MAXN = 2e5 + 123;

int t[4 * MAXN];

void Add(int v, int l, int r, int pos) {
    t[v] ++;
    if (l == r)
        return;
    int mid = l + (r - l) / 2;
    if (pos <= mid)
        Add(v * 2, l, mid, pos);
    else
        Add(v * 2 + 1, mid + 1, r, pos);
}

int Sum(int v, int l, int r, int ql, int qr) {
    if (l > qr || ql > r)
        return 0;
    if (l >= ql && r <= qr)
        return t[v];
    int mid = l + (r - l) / 2;
    return Sum(v * 2, l, mid, ql, qr) + Sum(v * 2 + 1, mid + 1, r, ql, qr);
}

ll count_swaps(vector<int> S) {
    ll res = 0;
    int n = S.size();
    vector<int> pos[n + 1] = {};
    for (int i = 0; i < n; i ++)
        pos[S[i] + n / 2].push_back(i);
    for (int i = 0; i <= n; i ++)
        reverse(pos[i].begin(), pos[i].end());

    vector<pair<int, int>> vec;
    for (int i = 0; i < n; i ++) {
        if (pos[S[i] + n / 2].back() != i)
            continue;
        vec.push_back({i, pos[-S[i] + n / 2].back()});
        pos[S[i] + n / 2].pop_back();
        pos[-S[i] + n / 2].pop_back();
        if (S[i] > 0) res ++;
    }

    for (auto [i, j] : vec) {
        int diff = j - i - 1;
        diff -= Sum(1, 0, n - 1, i + 1, j);
        res += diff;
        Add(1, 0, n - 1, j);
    }

    return res;
}

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