Submission #423758

#	Time	Username	Problem	Language	Result	Execution time	Memory
423758		Mazaalai	Arranging Shoes (IOI19_shoes)	C++17	45 / 100	398 ms	27168 KiB

shoes

#include "shoes.h"
#include <bits/stdc++.h>
typedef long long ll;
using namespace std;
ll ans = 0, n;
void countInv(vector <int>&s, int st, int end) {
	if (st == end) return;
	int mid = (st + end) / 2;
	countInv(s, st, mid);
	countInv(s, mid+1, end);
	vector <int> tmp, A, B;
	for (int i = st; i <= mid; i++) A.push_back(s[i]);
	for (int i = mid+1; i <= end; i++) B.push_back(s[i]);
	int inv = A.size();
	A.push_back(INT_MAX);
	B.push_back(INT_MAX);
	ll a = 0, b = 0;
	// for (int i = st; i <= end; i++) cout << s[i] << ' ';
	while(a + b + 2 < A.size() + B.size()) {
		if (A[a] <= B[b]) {
			tmp.push_back(A[a++]);
			inv--;
		} else {
			ans += inv;
			tmp.push_back(B[b++]);
		}
	}
	// ans += cur;
	// cout << ": " << cur  << ' ' << ans << '\n';
	for (int i = 0; i < tmp.size(); i++) s[i+st] = tmp[i];
}
long long count_swaps(vector<int> s) {
	ans = 0, n = s.size();
	map <int, vector <int> > l, r;
	for (int i = 0; i < n; i++) {
		if (s[i] < 0) 
			l[-s[i]].push_back(i);
		else
			r[s[i]].push_back(i);
	}
	vector <pair <int, int> > lines;
	for (auto el : l) {
		int val = el.first;
		vector <int> a = el.second, b = r[val];
		for (int i = 0; i < a.size(); i++) {
			int x = a[i], y = b[i];
			if (x > y) ans++;
			lines.push_back({x, y});
		}
	}
	int cur = 0;
	sort(lines.begin(), lines.end());
	for (int i = 0; i < lines.size(); i++) {
		int a, b;
		tie(a, b) = lines[i];
		s[a] = s[b] = cur++;
	}
	// for (int i = 0; i < n; i++) cout << s[i] << ' ';
	// cout << "\n";
	// cout << ans << " : ans\n";
	countInv(s, 0, n - 1);
	// for (int i = 0; i < n; i++) cout << s[i] << ' ';
	// cout << "\n";
	// cout << ans << " : ans\n";
	return ans;
}

Compilation message (stderr)

shoes.cpp: In function 'void countInv(std::vector<int>&, int, int)':
shoes.cpp:19:18: warning: comparison of integer expressions of different signedness: 'll' {aka 'long long int'} and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   19 |  while(a + b + 2 < A.size() + B.size()) {
      |        ~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~
shoes.cpp:30:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   30 |  for (int i = 0; i < tmp.size(); i++) s[i+st] = tmp[i];
      |                  ~~^~~~~~~~~~~~
shoes.cpp: In function 'long long int count_swaps(std::vector<int>)':
shoes.cpp:45:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   45 |   for (int i = 0; i < a.size(); i++) {
      |                   ~~^~~~~~~~~~
shoes.cpp:53:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   53 |  for (int i = 0; i < lines.size(); i++) {
      |                  ~~^~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 0 / 20
• Subtask 3: 20 / 20
• Subtask 4: 15 / 15
• Subtask 5: 0 / 20
• Subtask 6: 0 / 15