oj.uz

Submission #227055

# Submission time Handle Problem Language Result Execution time Memory
227055 2020-04-25T23:26:07 Z abeker Matching (COCI20_matching) C++17
58 / 110
 1120 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;
		}
		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;
Graph adj(MAXV), rev(MAXV);

inline int add_variables(int vars) {
	n += vars;
	assert(2 * n < MAXV);
	return n - vars;
}

void add_edge(int u, int v) {
	adj.add(u, v);
	rev.add(v, u);
}

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) {
	bio[x] = 1;
	for (Node* ptr = adj.head[x]; ptr != nullptr; ptr = ptr -> nxt)
		if (!bio[ptr -> val])
			dfs_forward(ptr -> val);
	order.push(x);
}

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

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

void two_sat() {
	for (int i = 0; i < 2 * n; i++)
		if (!bio[i])
			dfs_forward(i);
	for (int i = 0; i < 2 * n; i++)
		bio[i] = 0;
	for (; !order.empty(); order.pop())
		if (!bio[order.top()])
			dfs_backward(order.top());
}

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:132:8: 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:141:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  while (off[x] < tour[x].size())
         ~~~~~~~^~~~~~~~~~~~~~~~
matching.cpp: In function 'void load()':
matching.cpp:107:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &N);
  ~~~~~^~~~~~~~~~
matching.cpp:109:8: 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 260 ms 327036 KB Output is correct
2 Correct 226 ms 327032 KB Output is correct

Subtask #2
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 260 ms 327036 KB Output is correct
2 Correct 226 ms 327032 KB Output is correct
3 Correct 221 ms 327032 KB Output is correct
4 Correct 223 ms 327020 KB Output is correct
5 Correct 222 ms 327032 KB Output is correct
6 Correct 224 ms 327032 KB Output is correct
7 Correct 244 ms 327160 KB Output is correct

Subtask #3
7.0 / 7.0

# Verdict Execution time Memory Grader output
1 Correct 260 ms 327036 KB Output is correct
2 Correct 226 ms 327032 KB Output is correct
3 Correct 221 ms 327032 KB Output is correct
4 Correct 223 ms 327020 KB Output is correct
5 Correct 222 ms 327032 KB Output is correct
6 Correct 224 ms 327032 KB Output is correct
7 Correct 244 ms 327160 KB Output is correct
8 Correct 226 ms 327160 KB Output is correct
9 Correct 231 ms 327092 KB Output is correct
10 Correct 234 ms 327256 KB Output is correct
11 Correct 261 ms 327160 KB Output is correct
12 Correct 261 ms 327160 KB Output is correct

Subtask #4
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 260 ms 327036 KB Output is correct
2 Correct 226 ms 327032 KB Output is correct
3 Correct 221 ms 327032 KB Output is correct
4 Correct 223 ms 327020 KB Output is correct
5 Correct 222 ms 327032 KB Output is correct
6 Correct 224 ms 327032 KB Output is correct
7 Correct 244 ms 327160 KB Output is correct
8 Correct 226 ms 327160 KB Output is correct
9 Correct 231 ms 327092 KB Output is correct
10 Correct 234 ms 327256 KB Output is correct
11 Correct 261 ms 327160 KB Output is correct
12 Correct 261 ms 327160 KB Output is correct
13 Correct 268 ms 331256 KB Output is correct
14 Correct 235 ms 331384 KB Output is correct
15 Correct 250 ms 331388 KB Output is correct
16 Correct 250 ms 331384 KB Output is correct
17 Correct 240 ms 331256 KB Output is correct
18 Correct 234 ms 331232 KB Output is correct
19 Correct 230 ms 331256 KB Output is correct
20 Correct 263 ms 331384 KB Output is correct
21 Correct 240 ms 331256 KB Output is correct
22 Correct 238 ms 331256 KB Output is correct
23 Correct 237 ms 331640 KB Output is correct
24 Correct 242 ms 331640 KB Output is correct

Subtask #5
0 / 52.0

# Verdict Execution time Memory Grader output
1 Correct 260 ms 327036 KB Output is correct
2 Correct 226 ms 327032 KB Output is correct
3 Correct 221 ms 327032 KB Output is correct
4 Correct 223 ms 327020 KB Output is correct
5 Correct 222 ms 327032 KB Output is correct
6 Correct 224 ms 327032 KB Output is correct
7 Correct 244 ms 327160 KB Output is correct
8 Correct 226 ms 327160 KB Output is correct
9 Correct 231 ms 327092 KB Output is correct
10 Correct 234 ms 327256 KB Output is correct
11 Correct 261 ms 327160 KB Output is correct
12 Correct 261 ms 327160 KB Output is correct
13 Correct 268 ms 331256 KB Output is correct
14 Correct 235 ms 331384 KB Output is correct
15 Correct 250 ms 331388 KB Output is correct
16 Correct 250 ms 331384 KB Output is correct
17 Correct 240 ms 331256 KB Output is correct
18 Correct 234 ms 331232 KB Output is correct
19 Correct 230 ms 331256 KB Output is correct
20 Correct 263 ms 331384 KB Output is correct
21 Correct 240 ms 331256 KB Output is correct
22 Correct 238 ms 331256 KB Output is correct
23 Correct 237 ms 331640 KB Output is correct
24 Correct 242 ms 331640 KB Output is correct
25 Correct 963 ms 457820 KB Output is correct
26 Correct 971 ms 457828 KB Output is correct
27 Correct 962 ms 457832 KB Output is correct
28 Correct 1120 ms 458312 KB Output is correct
29 Correct 965 ms 457864 KB Output is correct
30 Correct 947 ms 457712 KB Output is correct
31 Correct 979 ms 457992 KB Output is correct
32 Correct 903 ms 457480 KB Output is correct
33 Correct 925 ms 445060 KB Output is correct
34 Correct 903 ms 445128 KB Output is correct
35 Correct 582 ms 433160 KB Output is correct
36 Runtime error 555 ms 524292 KB Execution killed with signal 9 (could be triggered by violating memory limits)
37 Halted 0 ms 0 KB -