Submission #501523

#	Time	Username	Problem	Language	Result	Execution time	Memory
501523		fusabile	Arranging Shoes (IOI19_shoes)	C++17	50 / 100	1052 ms	139356 KiB

shoes

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

#ifdef LOCAL
#include "dbg.h"
#else
#define dbg(...)
#endif
#define sz(s) (int)(s).size()
#define all(x) (x).begin(), (x).end()

typedef long long ll;
const int inf = INT_MAX;
const int dx[] = {1, -1, 0, 0};
const int dy[] = {0, 0, 1, -1};

queue<int> mp[200042];
inline int fix(int x)
{
	if (x < 0)
		x = 100000 - x;
	return x;
}
ll count_swaps(vector<int> S)
{
	int n = sz(S);
	ll ans = 0;
	//unordered_map<int, queue<int>> mp;
	for (int i = 0; i < n; i++)
	{
		mp[fix(S[i])].push(i);
	}
	
	vector<int> offset(n);
	for (int i = 0; i < n;)
	{
		if (S[i] == inf) 
		{
			i++;
			continue;
		}
		vector<array<int, 3>> best; // best[i] = {left_index, right_index, swap_count}
		int j = mp[fix(-S[i])].front();
		if (S[i] < 0)
			best.push_back({i, j, j - i - 1});
		else
			best.push_back({j, i, j - i});
		i++;
		if (abs(S[i]) != abs(S[i-1]))
		{
			if (S[i] < 0)
				best.push_back({i, j, j - i + 1});
			else
				best.push_back({j, i, j - i + 2});
		}
		i--;
		sort(best.begin(), best.end(), [](auto &x, auto &y) { return x[2] < y[2]; });
		auto [x, y, z] = best[0];
		ans += z - offset[i] + offset[j];
		if (min(x, y) == i + 1)
			offset[i] += 2;
		if (i + 1 <= j - 1)
		{
			for (int k = i + 1; k <= j - 1; k++)
				offset[k]++;
		}
		mp[fix(S[x])].pop();
		mp[fix(S[y])].pop();
		S[x] = inf;
		S[y] = inf;
	}
	return ans;	
}

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