Submission #469578

#	Time	Username	Problem	Language	Result	Execution time	Memory
469578		spike1236	Arranging Shoes (IOI19_shoes)	C++14	100 / 100	97 ms	13620 KiB

shoes

#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define mp make_pair
#define f first
#define s second
#define ll long long
#define ld long double
#define all(_v) _v.begin(), _v.end()
#define sz(_v) (int)_v.size()
#define pii pair <int, int>
#define pll pair <ll, ll>
#define veci vector <int>
#define vecll vector <ll>

const int dx[4] = {1, -1, 0, 0};
const int dy[4] = {0, 0, -1, 1};
const double PI = 3.1415926535897932384626433832795;
const double eps = 1e-9;
const int MOD1 = 1e9 + 7;
const int MOD2 = 998244353;

const int MAXN = 2e5 + 10;
int t[MAXN], n;
vector <pii> pos[MAXN];

void upd(int r, int val) {
    for(; r < MAXN; r += r & -r) t[r] += val;
}

int get(int r) {
    int res = 0;
    for(; r > 0; r -= r & -r) res += t[r];
    return res;
}

ll count_swaps(veci b) {
    n = sz(b) / 2;
    b.insert(b.begin(), 0);
    for(int i = 1; i <= 2 * n; ++i) {
        upd(i, 1);
        int x = b[i];
        pos[abs(x)].pb(mp(x, i));
    }
    ll ans = 0;
    vector <pii> seg;
    for(int i = 1; i <= n; ++i) {
        sort(all(pos[i]));
        for(int j = 0; j < sz(pos[i]) / 2; ++j) {
            int l = pos[i][j].s, r = pos[i][j + sz(pos[i]) / 2].s;
            if(l > r) ++ans, swap(l, r);
            seg.pb(mp(l, r));
        }
    }
    sort(all(seg));
    for(auto p : seg) {
        int l = p.f, r = p.s;
        ans += get(r - 1) - get(l);
        upd(l, -1);
        upd(r, -1);
    }
    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