Submission #292124

#	Time	Username	Problem	Language	Result	Execution time	Memory
292124		PeppaPig	Arranging Shoes (IOI19_shoes)	C++14	100 / 100	107 ms	20464 KiB

shoes

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

#define long long long
#define pii pair<int, int>
#define x first
#define y second

using namespace std;

const int N = 2e5 + 5;

int t[N];

void update(int x, int k) {
	for(int i = x; i < N; i += i & -i)
		t[i] += k;
}

int query(int x, int ret = 0) {
	for(int i = x; i; i -= i & -i)
		ret += t[i];
	return ret;
}

int n;
long ans = 0;
vector<int> l[N], r[N];

long count_swaps(vector<int> s) {
	n = (int)s.size();

	for(int i = 0; i < n; i++) {
		if(s[i] < 0) l[-s[i]].emplace_back(i + 1);
		else r[s[i]].emplace_back(i + 1);
	}

	vector<pii> vec;
	for(int i = 1; i <= n; i++) for(int j = 0; j < l[i].size(); j++) {
		int x = l[i][j], y = r[i][j];	
		if(x > y) swap(x, y), ++ans;
		vec.emplace_back(x, y);
	}

	sort(vec.begin(), vec.end());

	for(int i = 1; i <= n; i++) update(i, 1);
	for(pii p : vec) {
		ans += query(p.x) + query(p.y) - 3;
		update(p.x, -1), update(p.y, -1);
	}

	return ans;
}

Compilation message (stderr)

shoes.cpp: In function 'long long int count_swaps(std::vector<int>)':
shoes.cpp:39:47: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   39 |  for(int i = 1; i <= n; i++) for(int j = 0; j < l[i].size(); j++) {
      |                                             ~~^~~~~~~~~~~~~

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