Submission #271564

#	Time	Username	Problem	Language	Result	Execution time	Memory
271564		SeDunion	Arranging Shoes (IOI19_shoes)	C++14	100 / 100	163 ms	20472 KiB

shoes

#include "shoes.h"
#include <bits/stdc++.h>

using namespace std;
using ll = long long;
const int N = 2e5 + 55;

ll t[N];

void upd (int i, int v) {
	while (i < N) {
		t[i] += v;
		i |= (i + 1);
	}
}

ll getP (int i) {
	ll res = 0;
	while (i >= 0) {
		res += t[i];
		i &= (i + 1);
		--i;
	}
	return res;
}

ll get (int l, int r) {
	if (l > r) return 0;
	// assert (l <= r);
	return getP (r) - getP (l - 1);
}

vector <int> v[N * 2];

ll count_swaps (vector<int> s) {
	int n = s.size();
	for (int i = n - 1 ; i >= 0 ; -- i) {
		upd (i, 1);
		v[s[i] + N].push_back (i);
	}
	ll ans = 0;
	for (int i = 0 ; i < n ; ++ i) {
		if (get (i, i) == 0) continue;
		int x = s[i];
		int y = -s[i];
		assert (v[x + N].size() && v[y + N].size());
		int j = v[y + N].back();
		assert (i < j);
		v[y + N].pop_back();
		assert (v[x + N].back() == i);
		v[x + N].pop_back();
		ans += get (i + 1, j - 1);
		if (x > 0) ans++;
		upd (j, -1);
		upd (i, -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