Submission #143378

#	Time	Username	Problem	Language	Result	Execution time	Memory
143378		abeker	Arranging Shoes (IOI19_shoes)	C++17	10 / 100	18 ms	14456 KiB

shoes

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;

const int MAXN = 2e5 + 5;

int N;
vector <int> lft[MAXN], rig[MAXN], perm[MAXN];
	
ll inversions(vector <int> v) {
	reverse(v.begin(), v.end());
	int len = v.size();
	vector <int> fen(len + 1, 0);
	ll res = 0;
	for (auto it : v) {
		for (int x = it; x; x -= x & -x)
			res += fen[x];
		for (int x = it + 1; x <= len; x += x & -x)
			fen[x]++;
	}
	return res;
}

ll count_swaps(vector <int> shoes) {
	N = shoes.size();
	for (int i = 0; i < N; i++) {
		int sz = abs(shoes[i]);
		if (shoes[i] < 0) {
			perm[sz].push_back(2 * lft[sz].size());					
			lft[sz].push_back(i);
		}
		else {
			perm[sz].push_back(2 * rig[sz].size() + 1);
			rig[sz].push_back(i);
		}
	}
	
	ll sol = 0;
	for (int i = 0; i < N; i++) {
		sol += inversions(perm[i]);
		for (int j = 0; j < lft[i].size(); j++)
			sol += abs(lft[i][j] - rig[i][j]) - 1;
	}
	
	return sol;
}

Compilation message (stderr)

shoes.cpp: In function 'll count_swaps(std::vector<int>)':
shoes.cpp:42:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j = 0; j < lft[i].size(); j++)
                   ~~^~~~~~~~~~~~~~~

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