Submission #500285

#	Time	Username	Problem	Language	Result	Execution time	Memory
500285		pavement	Arranging Shoes (IOI19_shoes)	C++17	100 / 100	865 ms	351428 KiB

shoes

#include "shoes.h"
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;

typedef long long ll;

int seg[400005];
ll ans;
bool ed[400005];
vector<int> s;
queue<int> has[400005];
tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> ft[400005];

inline int ls(int x) { return x & -x; }

pair<int, int> qry(int p, int x) {
	pair<int, int> r = make_pair(0, 0);
	p = s.size() - p + 2;
	for (; p; p -= ls(p)) {
		r.first += ft[p].order_of_key(x);
		r.second += ft[p].size() - ft[p].order_of_key(x);
	}
	return r;
}

void upd(int p, int v) {
	p = s.size() - p + 2;
	for (; p <= s.size(); p += ls(p)) ft[p].insert(v);
}

ll count_swaps(vector<int> _s) {
	s = _s;
	for (int i = 0; i < s.size(); i++) {
		if (!has[-s[i] + s.size() / 2].empty()) {
			seg[i] = has[-s[i] + s.size() / 2].front();
			ed[i] = 1;
			if (s[i] < 0) ans++;
			has[-s[i] + s.size() / 2].pop();
		} else has[s[i] + s.size() / 2].push(i);
	}
	for (int i = 0; i < s.size(); i++) {
		if (!ed[i]) continue;
		pair<int, int> tmp = qry(seg[i] + 1, seg[i]);
		upd(i, seg[i]);
		ans += (ll)tmp.first + (ll)tmp.second * 2ll;
	}
	return ans;
}

Compilation message (stderr)

shoes.cpp: In function 'void upd(int, int)':
shoes.cpp:31:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   31 |  for (; p <= s.size(); p += ls(p)) ft[p].insert(v);
      |         ~~^~~~~~~~~~~
shoes.cpp: In function 'll count_swaps(std::vector<int>)':
shoes.cpp:36:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   36 |  for (int i = 0; i < s.size(); i++) {
      |                  ~~^~~~~~~~~~
shoes.cpp:44:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   44 |  for (int i = 0; i < s.size(); i++) {
      |                  ~~^~~~~~~~~~

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