Submission #610469

#	Time	Username	Problem	Language	Result	Execution time	Memory
610469		lorenzoferrari	Arranging Shoes (IOI19_shoes)	C++17	100 / 100	225 ms	21948 KiB

shoes

#include "shoes.h"
#include <bits/stdc++.h>
using namespace std;
using LL = long long;

struct Segment {
    int n;
    vector<int> t;
    Segment(int n, vector<int> v) : n(n) {
        t.resize(2 * n);
        for (int i = 0; i < n; ++i) {
            t[i + n] = v[i];
        }
        for (int i = n-1; i > 0; --i) {
            t[i] = t[2*i] + t[2*i+1];
        }
    }
    void upd(int i, int v) {
        for (t[i += n] = v; i > 1; i >>= 1) {
            t[i >> 1] = t[i] + t[i ^ 1];
        }
    }
    int sum(int l, int r) {
        int ans = 0;
        for (l += n, r += n; l < r; l >>= 1, r >>= 1) {
            if (l & 1) ans += t[l++];
            if (r & 1) ans += t[--r];
        }
        return ans;
    }
};

LL count_swaps(vector<int> s) {
    int n = s.size();
    map<int, array<vector<int>, 2>> mp;
    for (int i = 0; i < n; ++i) {
        mp[abs(s[i])][s[i] > 0].push_back(i);
    }
    vector<int> p(n);
    for (auto& [_, pairs] : mp) {
        assert(pairs[0].size() == pairs[1].size());
        for (int i = 0; i < (int)pairs[0].size(); ++i) {
            p[pairs[0][i]] = pairs[1][i];
            p[pairs[1][i]] = pairs[0][i];
        }
    }
    Segment st(n, vector<int>(n, 1));
    LL ans = 0;
    for (int i = 0; i < n; ++i) {
        if (p[i] < i) continue;
        ans += (s[i] > 0);
        st.upd(i, 0);
        st.upd(p[i], 0);
        ans += st.sum(i, p[i]);
    }
    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