Submission #421133

#	Time	Username	Problem	Language	Result	Execution time	Memory
421133		schse	Ancient Books (IOI17_books)	C++17	0 / 100	2 ms	784 KiB

books

#include "books.h"
#ifndef EVAL
#include "grader.cpp"
#endif

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

struct unionfind
{
	vector<int> root = vector<int>(1005);
	int find(int i)
	{
		if (root[i] == i)
			return i;
		return root[i] = find(root[i]);
	}
	bool unite(int a, int b)
	{
		a = find(a);
		b = find(b);
		if (a == b)
			return false;
		root[a] = b;
		return true;
	}
} un;

struct qnode
{
	int dis, a, b;
};

long long
minimum_walk(std::vector<int> p, int s)
{
	iota(un.root.begin(), un.root.end(), 0);
	vector<int> cycle(p.size(), -1);
	vector<vector<int>> cycles;
	long long triplenght = 0;

	for (int i = 0; i < p.size(); i++)
	{
		if (cycle[i] == -1 && p[i] != i)
		{
			int t = i;
			cycles.push_back({});
			do
			{
				cycles[cycles.size() - 1].push_back(t);
				cycle[t] = cycles.size();
				triplenght += abs(t - p[t]);
				t = p[t];
			} while (t != i);
		}
	}

	vector<qnode> edges;
	for (int i = 0; i < cycles.size(); i++)
	{
		for (int e = 0; e < i; e++)
		{
			int mn = INT32_MAX;
			for (int a : cycles[i])
				for (int b : cycles[e])
					mn = min(mn, abs(a - b));
			edges.push_back({mn, i, e});
		}
	}

	sort(edges.begin(), edges.end(), [](qnode a, qnode b)
		 { return a.dis < b.dis; });

	for (qnode n : edges)
	{
		if (un.unite(n.a, n.b))
			triplenght += 2 * n.dis;
	}
	int t = 0;

	while (cycles.size() && cycle[t++] == -1)
		triplenght += 2;

	return triplenght;
}

Compilation message (stderr)

books.cpp: In function 'long long int minimum_walk(std::vector<int>, int)':
books.cpp:42:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   42 |  for (int i = 0; i < p.size(); i++)
      |                  ~~^~~~~~~~~~
books.cpp:59:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   59 |  for (int i = 0; i < cycles.size(); i++)
      |                  ~~^~~~~~~~~~~~~~~

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