Submission #748848

#	Time	Username	Problem	Language	Result	Execution time	Memory
748848		wenqi	Ancient Books (IOI17_books)	C++17	50 / 100	237 ms	59564 KiB

books

#include "books.h"
#include <algorithm>
#include <cmath>
#include <queue>
#include <set>

using namespace std;
using ll = long long;

bool seen[1000005];
vector<int> P;
vector<int> t;

ll dfs(int i)
{
	if (seen[i])
		return 0;
	seen[i] = true;
	t.push_back(i);
	return abs(i - P[i]) + dfs(P[i]);
}

ll minimum_walk(vector<int> p, int s)
{
	P = p;
	ll sum = 0;
	int n = p.size();
	vector<pair<int, int>> q;
	q.push_back({s, s});
	for (int i = 0; i < n; i++)
	{
		if (seen[i] or i == p[i])
			continue;
		t.clear();
		sum += dfs(i);
		sort(t.begin(), t.end());
		q.push_back({t.front(), t.back()});
	}
	sort(q.begin(), q.end());
	int lt = -1;
	for (auto [a, b] : q)
	{
		if (lt == -1)
		{
			lt = b;
		}
		if (a > lt)
		{
			sum += 2 * (a - lt);
			lt = b;
		}
		else
		{
			lt = max(lt, b);
		}
	}
	return sum;
}

• Subtask 1: 12 / 12
• Subtask 2: 10 / 10
• Subtask 3: 28 / 28
• Subtask 4: 0 / 20
• Subtask 5: 0 / 30