oj.uz

Submission #856941

# Submission time Handle Problem Language Result Execution time Memory
856941 2023-10-04T23:29:15 Z mihajanez Thousands Islands (IOI22_islands) C++17
100 / 100
 112 ms 28556 KB 
#include <bits/stdc++.h>
#include <variant>
#include <vector>
#include <list>
#include <stack>
#include <queue>
using namespace std;


vector<int > construct_journey(
	vector<list<pair<int, int>>> nodes, int fork,
	list<pair<int, int>>c2, list<pair<int, int>>c1_fork_to_cycle_pairs, list<pair<int, int>>c1_cycle_pairs, bool two_cycles) {

	vector<int> journey;

	if (two_cycles) {
		list<int> start_to_fork, c1_fork_to_cycle, c1_cycle, c2_fork_to_cycle, c2_cycle;

		// component2
		int begin_cycle_c2 = c2.back().first;
		c2_cycle.push_front(c2.back().second);
		c2.pop_back();
		while (c2.back().first != begin_cycle_c2) {
			c2_cycle.push_front(c2.back().second);
			c2.pop_back();
		}
		while (c2.back().first != fork) {
			c2_fork_to_cycle.push_front(c2.back().second);
			c2.pop_back();
		}
		while (!c2.empty()) {
			start_to_fork.push_front(c2.back().second);
			c2.pop_back();
		}
		start_to_fork.pop_front();

		// component1
		for (auto& i : c1_fork_to_cycle_pairs) {
			c1_fork_to_cycle.push_back(i.second);
		}
		for (auto& i : c1_cycle_pairs) {
			c1_cycle.push_back(i.second);
		}

		journey.reserve(2 * start_to_fork.size() + 4 * c1_fork_to_cycle.size() + 2 * c1_cycle.size() + 4 * c2_fork_to_cycle.size() + 2 * c2_cycle.size());
		copy(start_to_fork.cbegin(), start_to_fork.cend(), back_inserter(journey));
		copy(c1_fork_to_cycle.cbegin(), c1_fork_to_cycle.cend(), back_inserter(journey));
		copy(c1_cycle.cbegin(), c1_cycle.cend(), back_inserter(journey));
		copy(c1_fork_to_cycle.crbegin(), c1_fork_to_cycle.crend(), back_inserter(journey));
		copy(c2_fork_to_cycle.cbegin(), c2_fork_to_cycle.cend(), back_inserter(journey));
		copy(c2_cycle.cbegin(), c2_cycle.cend(), back_inserter(journey));
		copy(c2_fork_to_cycle.crbegin(), c2_fork_to_cycle.crend(), back_inserter(journey));
		copy(c1_fork_to_cycle.cbegin(), c1_fork_to_cycle.cend(), back_inserter(journey));
		copy(c1_cycle.crbegin(), c1_cycle.crend(), back_inserter(journey));
		copy(c1_fork_to_cycle.crbegin(), c1_fork_to_cycle.crend(), back_inserter(journey));
		copy(c2_fork_to_cycle.cbegin(), c2_fork_to_cycle.cend(), back_inserter(journey));
		copy(c2_cycle.crbegin(), c2_cycle.crend(), back_inserter(journey));
		copy(c2_fork_to_cycle.crbegin(), c2_fork_to_cycle.crend(), back_inserter(journey));
		copy(start_to_fork.crbegin(), start_to_fork.crend(), back_inserter(journey));
	}
	else {
		list<int> start_to_fork, fork_to_join1, fork_to_join2, cycle;

		// component2
		while (c2.front().first != fork) {
			start_to_fork.push_back(c2.front().second);
			c2.pop_front();
		}
		start_to_fork.push_back(c2.front().second);
		start_to_fork.pop_front();
		c2.pop_front();
		for (auto& i : c2) {
			fork_to_join2.push_back(i.second);
		}

		for (auto& i : c1_cycle_pairs) {
			cycle.push_back(i.second);
		}

		int join = c2.back().first;
		// component1
		auto it = c1_fork_to_cycle_pairs.cbegin();
		while (it != c1_fork_to_cycle_pairs.cend() && (*it).first != join) {
			fork_to_join1.push_back((*it++).second);
		}

		// join before the cycle
		if (it != c1_fork_to_cycle_pairs.cend()) {
			fork_to_join1.push_back((*it++).second);
			list<int> join_to_cycle;
			while (it != c1_fork_to_cycle_pairs.cend()) {
				join_to_cycle.push_back((*it++).second);
			}

			journey.reserve(2 * start_to_fork.size() + 2 * fork_to_join1.size() + 2 * fork_to_join2.size() + 4 * join_to_cycle.size() + 2 * cycle.size());
			copy(start_to_fork.cbegin(), start_to_fork.cend(), back_inserter(journey));
			copy(fork_to_join1.cbegin(), fork_to_join1.cend(), back_inserter(journey));
			copy(join_to_cycle.cbegin(), join_to_cycle.cend(), back_inserter(journey));
			copy(cycle.cbegin(), cycle.cend(), back_inserter(journey));
			copy(join_to_cycle.crbegin(), join_to_cycle.crend(), back_inserter(journey));
			copy(fork_to_join1.crbegin(), fork_to_join1.crend(), back_inserter(journey));
			copy(fork_to_join2.cbegin(), fork_to_join2.cend(), back_inserter(journey));
			copy(join_to_cycle.cbegin(), join_to_cycle.cend(), back_inserter(journey));
			copy(cycle.crbegin(), cycle.crend(), back_inserter(journey));
			copy(join_to_cycle.crbegin(), join_to_cycle.crend(), back_inserter(journey));
			copy(fork_to_join2.crbegin(), fork_to_join2.crend(), back_inserter(journey));
			copy(start_to_fork.crbegin(), start_to_fork.crend(), back_inserter(journey));
		}

		// join inside the cycle
		else {
			journey.reserve(2 * start_to_fork.size() + 2 * fork_to_join1.size() + 2 * fork_to_join2.size() + 2 * cycle.size());
			copy(start_to_fork.cbegin(), start_to_fork.cend(), back_inserter(journey));
			copy(fork_to_join1.cbegin(), fork_to_join1.cend(), back_inserter(journey));
			copy(cycle.cbegin(), cycle.cend(), back_inserter(journey));
			copy(fork_to_join1.crbegin(), fork_to_join1.crend(), back_inserter(journey));
			copy(fork_to_join2.cbegin(), fork_to_join2.cend(), back_inserter(journey));
			// rotate the cycle
			while (c1_cycle_pairs.back().first != join) {
				c1_cycle_pairs.push_front(c1_cycle_pairs.back());
				c1_cycle_pairs.pop_back();
				cycle.push_front(cycle.back());
				cycle.pop_back();
			}
			copy(cycle.crbegin(), cycle.crend(), back_inserter(journey));
			copy(fork_to_join2.crbegin(), fork_to_join2.crend(), back_inserter(journey));
			copy(start_to_fork.crbegin(), start_to_fork.crend(), back_inserter(journey));
		}
	}
	return journey;
}


list<pair<int, int>> construct_cycle(vector<list<pair<int, int>>> nodes, int begin_cycle, vector<bool> unavailable_nodes) {
	vector<bool> visited(nodes.size(), false);
	vector<pair<int, int>> predecessors(nodes.size());
	queue<int> bfs_queue;

	visited[begin_cycle] = true;
	bfs_queue.push(begin_cycle);
	while (!bfs_queue.empty()) {
		int last_node = bfs_queue.front();
		bfs_queue.pop();

		for (auto& next_edge : nodes[last_node]) {
			if (!visited[next_edge.first] && !unavailable_nodes[next_edge.first]) {
				visited[next_edge.first] = true;
				bfs_queue.push(next_edge.first);
				predecessors[next_edge.first] = make_pair(last_node, next_edge.second);
			}
			else if (next_edge.first == begin_cycle) {
				list<pair<int, int>> cycle;
				cycle.push_front(make_pair(next_edge.first, next_edge.second));
				while (last_node != begin_cycle) {
					cycle.push_front(make_pair(last_node, predecessors[last_node].second));
					last_node = predecessors[last_node].first;
				}
				return cycle;
			}
		}
	}
	return {};
}


variant<bool, vector<int>> find_journey(int N, int M, vector<int> U, vector<int> V) {
	// pair out_node, out_edge
	vector<list<pair<int, int>>> nodes(N);
	for (auto i = 0; i < U.size(); i++) {
		nodes[U[i]].push_back(make_pair(V[i], i));
	}

	vector<bool>
		visited(nodes.size(), false),
		in_path(nodes.size(), false),
		begin_cycle(nodes.size(), false),
		goal(nodes.size(), false);
	stack<list<pair<int, int>>::const_iterator> dfs_stack;
	list<pair<int, int>> path;
	list<pair<int, int>> c1_fork_to_cycle, c1_cycle;
	bool seek_component2 = false;
	int fork = -1;

	visited[0] = true;
	in_path[0] = true;
	dfs_stack.push(nodes[0].cbegin());
	path.push_back(make_pair(0, -1));
	while (!dfs_stack.empty()) {
		int top_node = path.back().first;

		goal[top_node] = seek_component2;

		// first popped cycle -> found the cycle of component1
		if (!seek_component2 && begin_cycle[top_node]) {
			seek_component2 = true;
			c1_cycle = construct_cycle(nodes, top_node, in_path);
			visited = vector<bool>(nodes.size(), false);
			for (auto& i : c1_cycle) {
				visited[i.first] = true;
				goal[i.first] = true;
			}
			for (auto& i : path) {
				visited[i.first] = true;
			}
		}

		// top_node has more successors
		if (dfs_stack.top() != nodes[path.back().first].cend()) {
			auto& [successor_node, successor_edge] = *dfs_stack.top();
			dfs_stack.top()++;

			// set new fork
			if (seek_component2 && fork == -1) {
				fork = top_node;
			}

			if (!visited[successor_node]) {
				visited[successor_node] = true;
				in_path[successor_node] = true;
				dfs_stack.push(nodes[successor_node].cbegin());
				path.push_back(make_pair(successor_node, successor_edge));
			}
			// found a cycle in component1
			else if (!seek_component2 && in_path[successor_node]) {
				begin_cycle[successor_node] = true;
			}
			// found component2
			else if (goal[successor_node]) {
				path.push_back(make_pair(successor_node, successor_edge));
				// cycle found
				if (in_path[successor_node]) {
					return construct_journey(nodes, fork, path, c1_fork_to_cycle, c1_cycle, true);
				}
				// path to component1 found
				else {
					return construct_journey(nodes, fork, path, c1_fork_to_cycle, c1_cycle, false);
				}
			}
		}
		// top_node has no more successors -> pop it off the stack
		else {
			goal[top_node] = false;
			if (top_node == fork) {
				fork = -1;
			}
			if (seek_component2 && fork == -1) {
				goal[top_node] = true;
				c1_fork_to_cycle.push_front(path.back());
			}

			in_path[top_node] = false;
			dfs_stack.pop();
			path.pop_back();
		}
	}
	return false;
}

Compilation message

islands.cpp: In function 'std::variant<bool, std::vector<int, std::allocator<int> > > find_journey(int, int, std::vector<int>, std::vector<int>)':
islands.cpp:169:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  169 |  for (auto i = 0; i < U.size(); i++) {
      |                   ~~^~~~~~~~~~

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 344 KB Output is correct
2 Correct 0 ms 348 KB Output is correct
3 Correct 0 ms 348 KB Output is correct
4 Correct 0 ms 348 KB Output is correct
5 Correct 1 ms 604 KB Output is correct
6 Correct 1 ms 348 KB Output is correct
7 Correct 51 ms 16836 KB Output is correct

Subtask #2
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 348 KB Output is correct
2 Correct 1 ms 348 KB Output is correct
3 Correct 0 ms 344 KB Output is correct
4 Correct 0 ms 348 KB Output is correct
5 Correct 0 ms 440 KB Output is correct
6 Correct 46 ms 13904 KB Output is correct

Subtask #3
21.0 / 21.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 600 KB Output is correct
2 Correct 0 ms 348 KB Output is correct
3 Correct 0 ms 432 KB Output is correct
4 Correct 0 ms 348 KB Output is correct
5 Correct 1 ms 704 KB Output is correct
6 Correct 1 ms 436 KB Output is correct
7 Correct 1 ms 436 KB Output is correct
8 Correct 1 ms 432 KB Output is correct
9 Correct 0 ms 348 KB Output is correct
10 Correct 1 ms 604 KB Output is correct
11 Correct 0 ms 548 KB Output is correct
12 Correct 1 ms 604 KB Output is correct
13 Correct 0 ms 348 KB Output is correct
14 Correct 0 ms 348 KB Output is correct
15 Correct 1 ms 348 KB Output is correct
16 Correct 0 ms 348 KB Output is correct
17 Correct 27 ms 9024 KB Output is correct
18 Correct 22 ms 7260 KB Output is correct
19 Correct 0 ms 348 KB Output is correct
20 Correct 1 ms 348 KB Output is correct
21 Correct 0 ms 344 KB Output is correct
22 Correct 0 ms 348 KB Output is correct
23 Correct 45 ms 13908 KB Output is correct

Subtask #4
24.0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 348 KB Output is correct
2 Correct 1 ms 604 KB Output is correct
3 Correct 61 ms 15784 KB Output is correct
4 Correct 55 ms 15700 KB Output is correct
5 Correct 2 ms 604 KB Output is correct
6 Correct 1 ms 604 KB Output is correct
7 Correct 0 ms 392 KB Output is correct
8 Correct 0 ms 348 KB Output is correct
9 Correct 0 ms 348 KB Output is correct
10 Correct 1 ms 604 KB Output is correct
11 Correct 1 ms 604 KB Output is correct
12 Correct 2 ms 604 KB Output is correct
13 Correct 2 ms 604 KB Output is correct
14 Correct 2 ms 752 KB Output is correct
15 Correct 2 ms 856 KB Output is correct
16 Correct 1 ms 604 KB Output is correct
17 Correct 0 ms 348 KB Output is correct
18 Correct 2 ms 604 KB Output is correct
19 Correct 1 ms 604 KB Output is correct
20 Correct 37 ms 10824 KB Output is correct
21 Correct 79 ms 15760 KB Output is correct
22 Correct 1 ms 612 KB Output is correct
23 Correct 0 ms 348 KB Output is correct
24 Correct 0 ms 348 KB Output is correct
25 Correct 1 ms 604 KB Output is correct
26 Correct 1 ms 704 KB Output is correct
27 Correct 55 ms 16564 KB Output is correct
28 Correct 65 ms 16832 KB Output is correct
29 Correct 0 ms 344 KB Output is correct
30 Correct 39 ms 11344 KB Output is correct
31 Correct 0 ms 344 KB Output is correct
32 Correct 63 ms 15956 KB Output is correct
33 Correct 60 ms 16224 KB Output is correct
34 Correct 27 ms 9132 KB Output is correct
35 Correct 1 ms 600 KB Output is correct
36 Correct 44 ms 14064 KB Output is correct
37 Correct 62 ms 16720 KB Output is correct
38 Correct 1 ms 348 KB Output is correct
39 Correct 29 ms 8804 KB Output is correct
40 Correct 1 ms 600 KB Output is correct
41 Correct 38 ms 11344 KB Output is correct
42 Correct 61 ms 16804 KB Output is correct
43 Correct 0 ms 344 KB Output is correct
44 Correct 1 ms 604 KB Output is correct
45 Correct 2 ms 604 KB Output is correct
46 Correct 22 ms 7220 KB Output is correct

Subtask #5
45.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 344 KB Output is correct
2 Correct 0 ms 348 KB Output is correct
3 Correct 0 ms 348 KB Output is correct
4 Correct 0 ms 348 KB Output is correct
5 Correct 1 ms 604 KB Output is correct
6 Correct 1 ms 348 KB Output is correct
7 Correct 51 ms 16836 KB Output is correct
8 Correct 0 ms 348 KB Output is correct
9 Correct 1 ms 348 KB Output is correct
10 Correct 0 ms 344 KB Output is correct
11 Correct 0 ms 348 KB Output is correct
12 Correct 0 ms 440 KB Output is correct
13 Correct 46 ms 13904 KB Output is correct
14 Correct 1 ms 600 KB Output is correct
15 Correct 0 ms 348 KB Output is correct
16 Correct 0 ms 432 KB Output is correct
17 Correct 0 ms 348 KB Output is correct
18 Correct 1 ms 704 KB Output is correct
19 Correct 1 ms 436 KB Output is correct
20 Correct 1 ms 436 KB Output is correct
21 Correct 1 ms 432 KB Output is correct
22 Correct 0 ms 348 KB Output is correct
23 Correct 1 ms 604 KB Output is correct
24 Correct 0 ms 548 KB Output is correct
25 Correct 1 ms 604 KB Output is correct
26 Correct 0 ms 348 KB Output is correct
27 Correct 0 ms 348 KB Output is correct
28 Correct 1 ms 348 KB Output is correct
29 Correct 0 ms 348 KB Output is correct
30 Correct 27 ms 9024 KB Output is correct
31 Correct 22 ms 7260 KB Output is correct
32 Correct 0 ms 348 KB Output is correct
33 Correct 1 ms 348 KB Output is correct
34 Correct 0 ms 344 KB Output is correct
35 Correct 0 ms 348 KB Output is correct
36 Correct 45 ms 13908 KB Output is correct
37 Correct 0 ms 344 KB Output is correct
38 Correct 0 ms 600 KB Output is correct
39 Correct 1 ms 348 KB Output is correct
40 Correct 1 ms 344 KB Output is correct
41 Correct 22 ms 7784 KB Output is correct
42 Correct 2 ms 860 KB Output is correct
43 Correct 30 ms 12344 KB Output is correct
44 Correct 33 ms 12376 KB Output is correct
45 Correct 37 ms 12376 KB Output is correct
46 Correct 0 ms 348 KB Output is correct
47 Correct 0 ms 348 KB Output is correct
48 Correct 1 ms 348 KB Output is correct
49 Correct 1 ms 604 KB Output is correct
50 Correct 78 ms 23580 KB Output is correct
51 Correct 51 ms 16464 KB Output is correct
52 Correct 81 ms 23492 KB Output is correct
53 Correct 80 ms 23356 KB Output is correct
54 Correct 62 ms 24320 KB Output is correct
55 Correct 75 ms 24268 KB Output is correct
56 Correct 112 ms 24144 KB Output is correct
57 Correct 57 ms 21532 KB Output is correct
58 Correct 74 ms 21656 KB Output is correct
59 Correct 70 ms 14420 KB Output is correct
60 Correct 67 ms 23896 KB Output is correct
61 Correct 44 ms 14656 KB Output is correct
62 Correct 7 ms 3164 KB Output is correct
63 Correct 42 ms 13924 KB Output is correct
64 Correct 30 ms 9044 KB Output is correct
65 Correct 0 ms 344 KB Output is correct
66 Correct 1 ms 348 KB Output is correct
67 Correct 88 ms 24672 KB Output is correct
68 Correct 50 ms 11344 KB Output is correct
69 Correct 27 ms 9808 KB Output is correct
70 Correct 1 ms 604 KB Output is correct
71 Correct 40 ms 10332 KB Output is correct
72 Correct 0 ms 344 KB Output is correct
73 Correct 63 ms 13648 KB Output is correct
74 Correct 74 ms 24668 KB Output is correct
75 Correct 3 ms 1372 KB Output is correct
76 Correct 33 ms 11416 KB Output is correct
77 Correct 43 ms 18004 KB Output is correct
78 Correct 66 ms 23888 KB Output is correct
79 Correct 0 ms 348 KB Output is correct
80 Correct 108 ms 28556 KB Output is correct
81 Correct 1 ms 604 KB Output is correct
82 Correct 37 ms 10572 KB Output is correct
83 Correct 1 ms 348 KB Output is correct
84 Correct 0 ms 348 KB Output is correct
85 Correct 33 ms 10592 KB Output is correct
86 Correct 1 ms 600 KB Output is correct
87 Correct 2 ms 2396 KB Output is correct
88 Correct 2 ms 1112 KB Output is correct
89 Correct 68 ms 23884 KB Output is correct
90 Correct 52 ms 14420 KB Output is correct
91 Correct 108 ms 28140 KB Output is correct
92 Correct 0 ms 344 KB Output is correct