oj.uz

Submission #227057

# Submission time Handle Problem Language Result Execution time Memory
227057 2020-04-25T23:55:58 Z abeker Matching (COCI20_matching) C++17
58 / 110
 848 ms 524292 KB 
#include <bits/stdc++.h>
using namespace std;
 
typedef pair <int, int> pii;
 
const int MAXN = 1e5 + 5;
const int offset = 1 << 17;
const int MAXV = 2e7 + 5;

struct Node {
	int val;
	Node* nxt;
};

class Graph {
	Node* get_node(int dest, Node* head) {
		Node* newNode = new Node;
		newNode -> val = dest;
		newNode -> nxt = head;
		return newNode;
	}
	int N;
	public:
		Node **head;
		Graph(int N) {
			head = new Node*[N]();
			this -> N = N;
			for (int i = 0; i < N; i++)
				head[i] = nullptr;
		}
		Graph(){}
		void add(int src, int dest) {
			head[src] = get_node(dest, head[src]);
		}
		~Graph() {
			for (int i = 0; i < N; i++)
				delete[] head[i];
			delete[] head;
		}
};

int n;
bool sol[MAXV];
char bio[MAXV];
stack <int> order;
pii edges[MAXV];
int e;

inline int add_variables(int vars) {
	n += vars;
	return n - vars;
}

void add_edge(int u, int v) {
	edges[e++] = {u, v};
}

void add_implication(int u1, int neg1, int u2, int neg2) {
	add_edge(2 * u1 + neg1, 2 * u2 + neg2);
	add_edge(2 * u2 + !neg2, 2 * u1 + !neg1);
}

void dfs_forward(int x, Graph &g) {
	bio[x] = 1;
	for (Node* ptr = g.head[x]; ptr != nullptr; ptr = ptr -> nxt)
		if (!bio[ptr -> val])
			dfs_forward(ptr -> val, g);
	order.push(x);
}

void bye() {
	puts("NE");
	exit(0);
}

void dfs_backward(int x, Graph &g) {
	if (bio[x ^ 1] == -1)
		bye();
	bio[x] = -1;
	sol[x] = bio[x ^ 1];
	for (Node* ptr = g.head[x]; ptr != nullptr; ptr = ptr -> nxt)
		if (!bio[ptr -> val])
			dfs_backward(ptr -> val, g);
	bio[x] = 1;
}

void two_sat() {
	Graph adj(2 * n), rev(2 * n);
	for (int i = 0; i < e; i++) {
		adj.add(edges[i].first, edges[i].second);
		rev.add(edges[i].second, edges[i].first);
	}
	for (int i = 0; i < 2 * n; i++)
		if (!bio[i])
			dfs_forward(i, adj);
	for (int i = 0; i < 2 * n; i++)
		bio[i] = 0;
	for (; !order.empty(); order.pop())
		if (!bio[order.top()])
			dfs_backward(order.top(), rev);
}

int N;
int x[MAXN], y[MAXN];
vector <pii> tour[2 * offset];
int st[2 * offset], off[2 * offset];
vector <int> hor[MAXN], ver[MAXN];
unordered_map <int, pii> segs;
vector <int> graph[MAXN];
 
void load() {
	scanf("%d", &N);
	for (int i = 0; i < N; i++) {
		scanf("%d%d", x + i, y + i);
		hor[y[i]].push_back(i);
		ver[x[i]].push_back(i);
	}
}
 
void insert(int x, int lo, int hi, int from, int to, int var, int height) {
	if (lo >= to || hi <= from)	
		return;
	if (lo >= from && hi <= to) {
		tour[x].push_back({height, var});
		return;
	}
	int mid = (lo + hi) / 2;
	insert(2 * x, lo, mid, from, to, var, height);
	insert(2 * x + 1, mid, hi, from, to, var, height);
}
 
inline int get_id(int node, int x) {
	return x < off[node] ? st[node] + x : tour[node][x - off[node]].second;
}
 
void add_clause(int x, int u, int v) {
	if (u < off[x] + tour[x].size())
		add_implication(get_id(x, u), 0, get_id(x, v), 0);
}
	
void init(int x) {
	if (tour[x].empty())
		return;
	off[x] = 1;
	sort(tour[x].begin(), tour[x].end());
	while (off[x] < tour[x].size())
		off[x] *= 2;
	st[x] = add_variables(2 * off[x]);
	for (int i = 0; i < off[x]; i++) {
		add_clause(x, 2 * i, i);
		add_clause(x, 2 * i + 1, i);
	}
}
 
int get_bounds(int x, int val) {
	int lo = 0, hi = tour[x].size();
	while (lo < hi) {
		int mid = (lo + hi) / 2;
		if (tour[x][mid].first >= val)
			hi = mid;
		else
			lo = mid + 1;
	}
	return lo;
}
 
void update(int node, int from, int to, int var) {
	from += off[node];
	to += off[node];
	while (from < to) {
		if (from % 2) 
			add_implication(get_id(node, from++), 0, var, 1);
		if (to % 2) 
			add_implication(get_id(node, --to), 0, var, 1);
		from /= 2;
		to /= 2;
	}
}
 
void add_intersections(int x, int down, int up, int var) {
	for (x += offset; x; x /= 2) 
		if (off[x])
			update(x, get_bounds(x, down), get_bounds(x, up + 1), var);
}
 
void solve() {
	for (int i = 1; i < MAXN; i++) 
		if (hor[i].size() == 2) {
			int tmp = add_variables(1);
			segs[tmp] = {hor[i][0], hor[i][1]};
			int l = MAXN, r = 0;
			for (auto it : hor[i]) {
				graph[it].push_back(tmp);
				l = min(l, x[it]);
				r = max(r, x[it]);
			}
			insert(1, 0, offset, l, r + 1, tmp, i);
		}
	
	for (int i = 0; i < 2 * offset; i++)
		init(i);
	
	for (int i = 1; i < MAXN; i++) 
		if (ver[i].size() == 2) {
			int tmp = add_variables(1);
			segs[tmp] = {ver[i][0], ver[i][1]};
			int l = MAXN, r = 0;
			for (auto it : ver[i]) {
				graph[it].push_back(tmp);
				l = min(l, y[it]);
				r = max(r, y[it]);
			}
			add_intersections(i, l, r, tmp);
		}
	
	for (int i = 0; i < N; i++) 
		if (!graph[i].empty())
			add_implication(graph[i][0], 1, graph[i][1 % graph[i].size()], 0);
		else
			bye();
	
	two_sat();
	
	puts("DA");
	for (auto it : segs)
		if (sol[2 * it.first])
			printf("%d %d\n", it.second.first + 1, it.second.second + 1);
}
 
int main() {
	double timer = clock();
	load();
	solve();
	fprintf(stderr, "%lf\n", (clock() - timer) / CLOCKS_PER_SEC);
	return 0;
}

Compilation message

matching.cpp: In function 'void add_clause(int, int, int)':
matching.cpp:137:8: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  if (u < off[x] + tour[x].size())
      ~~^~~~~~~~~~~~~~~~~~~~~~~~~
matching.cpp: In function 'void init(int)':
matching.cpp:146:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  while (off[x] < tour[x].size())
         ~~~~~~~^~~~~~~~~~~~~~~~
matching.cpp: In function 'void load()':
matching.cpp:112:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &N);
  ~~~~~^~~~~~~~~~
matching.cpp:114:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d", x + i, y + i);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~~

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 13952 KB Output is correct
2 Correct 13 ms 13824 KB Output is correct

Subtask #2
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 13952 KB Output is correct
2 Correct 13 ms 13824 KB Output is correct
3 Correct 12 ms 13824 KB Output is correct
4 Correct 12 ms 13824 KB Output is correct
5 Correct 13 ms 13824 KB Output is correct
6 Correct 12 ms 13952 KB Output is correct
7 Correct 12 ms 13824 KB Output is correct

Subtask #3
7.0 / 7.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 13952 KB Output is correct
2 Correct 13 ms 13824 KB Output is correct
3 Correct 12 ms 13824 KB Output is correct
4 Correct 12 ms 13824 KB Output is correct
5 Correct 13 ms 13824 KB Output is correct
6 Correct 12 ms 13952 KB Output is correct
7 Correct 12 ms 13824 KB Output is correct
8 Correct 13 ms 14080 KB Output is correct
9 Correct 13 ms 14080 KB Output is correct
10 Correct 13 ms 14080 KB Output is correct
11 Correct 13 ms 14080 KB Output is correct
12 Correct 13 ms 14080 KB Output is correct

Subtask #4
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 13952 KB Output is correct
2 Correct 13 ms 13824 KB Output is correct
3 Correct 12 ms 13824 KB Output is correct
4 Correct 12 ms 13824 KB Output is correct
5 Correct 13 ms 13824 KB Output is correct
6 Correct 12 ms 13952 KB Output is correct
7 Correct 12 ms 13824 KB Output is correct
8 Correct 13 ms 14080 KB Output is correct
9 Correct 13 ms 14080 KB Output is correct
10 Correct 13 ms 14080 KB Output is correct
11 Correct 13 ms 14080 KB Output is correct
12 Correct 13 ms 14080 KB Output is correct
13 Correct 30 ms 19092 KB Output is correct
14 Correct 23 ms 19072 KB Output is correct
15 Correct 22 ms 19024 KB Output is correct
16 Correct 23 ms 18944 KB Output is correct
17 Correct 23 ms 18944 KB Output is correct
18 Correct 25 ms 18944 KB Output is correct
19 Correct 23 ms 18944 KB Output is correct
20 Correct 22 ms 18944 KB Output is correct
21 Correct 20 ms 18944 KB Output is correct
22 Correct 21 ms 19072 KB Output is correct
23 Correct 25 ms 19712 KB Output is correct
24 Correct 23 ms 19704 KB Output is correct

Subtask #5
0 / 52.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 13952 KB Output is correct
2 Correct 13 ms 13824 KB Output is correct
3 Correct 12 ms 13824 KB Output is correct
4 Correct 12 ms 13824 KB Output is correct
5 Correct 13 ms 13824 KB Output is correct
6 Correct 12 ms 13952 KB Output is correct
7 Correct 12 ms 13824 KB Output is correct
8 Correct 13 ms 14080 KB Output is correct
9 Correct 13 ms 14080 KB Output is correct
10 Correct 13 ms 14080 KB Output is correct
11 Correct 13 ms 14080 KB Output is correct
12 Correct 13 ms 14080 KB Output is correct
13 Correct 30 ms 19092 KB Output is correct
14 Correct 23 ms 19072 KB Output is correct
15 Correct 22 ms 19024 KB Output is correct
16 Correct 23 ms 18944 KB Output is correct
17 Correct 23 ms 18944 KB Output is correct
18 Correct 25 ms 18944 KB Output is correct
19 Correct 23 ms 18944 KB Output is correct
20 Correct 22 ms 18944 KB Output is correct
21 Correct 20 ms 18944 KB Output is correct
22 Correct 21 ms 19072 KB Output is correct
23 Correct 25 ms 19712 KB Output is correct
24 Correct 23 ms 19704 KB Output is correct
25 Correct 781 ms 178312 KB Output is correct
26 Correct 848 ms 178056 KB Output is correct
27 Correct 719 ms 178056 KB Output is correct
28 Correct 820 ms 178952 KB Output is correct
29 Correct 515 ms 178476 KB Output is correct
30 Correct 691 ms 178312 KB Output is correct
31 Correct 615 ms 178564 KB Output is correct
32 Correct 525 ms 178180 KB Output is correct
33 Correct 483 ms 162432 KB Output is correct
34 Correct 445 ms 162560 KB Output is correct
35 Correct 160 ms 40072 KB Output is correct
36 Runtime error 804 ms 524292 KB Execution killed with signal 9 (could be triggered by violating memory limits)
37 Halted 0 ms 0 KB -