oj.uz

Submission #460945

# Submission time Handle Problem Language Result Execution time Memory
460945 2021-08-09T11:19:35 Z kingfran1907 Pipes (CEOI15_pipes) C++14
100 / 100
 1619 ms 13952 KB 
#include <bits/stdc++.h>
#define X first
#define Y second

using namespace std;
typedef long long llint;

const int maxn = 1e5+10;
const int base = 31337;
const int mod = 1e9+7;
const int inf = 0x3f3f3f3f;
const int logo = 18;
const int off = 1 << logo;
const int treesiz = off << 1;

struct union_find {
	int parr[maxn];
	
	union_find() {
		for (int i = 0; i < maxn; i++) parr[i] = i;
	}
	
	int fin(int x) {
		if (x == parr[x]) return x;
		return parr[x] = fin(parr[x]);
	}
	
	void merg(int a, int b) {
		a = fin(a);
		b = fin(b);
		if (a == b) return;
		
		int ra = rand() % 2;
		if (ra == 0) parr[b] = a;
		else parr[a] = b;
	}
};

int n, m;
vector< int > graph[maxn];
union_find p, q;
int t = 0;
int dis[maxn], lo[maxn];

void dfs(int x, int parr) {
	dis[x] = t++;
	lo[x] = dis[x];
	//printf("start %d %d\n", x, dis[x]);
	
	bool flag = false;
	for (int tren : graph[x]) {
		if (tren == parr && !flag) {
			flag = true;
			continue;
		}
		if (dis[tren] == -1) {
			dfs(tren, x);
			if (lo[tren] > dis[x]) printf("%d %d\n", x, tren);
			lo[x] = min(lo[x], lo[tren]);
		} else {
			lo[x] = min(lo[x], dis[tren]);
		}
	}
	//printf("end %d: %d %d\n", x, dis[x], lo[x]);
}

int main() {
	srand(time(0));
	scanf("%d%d", &n, &m);
	for (int i = 0; i < m; i++) {
		int a, b;
		scanf("%d%d", &a, &b);
		
		if (p.fin(a) != p.fin(b)) {
			graph[a].push_back(b);
			graph[b].push_back(a);
			
			p.merg(a, b);
		} else if (q.fin(a) != q.fin(b)) {
			graph[a].push_back(b);
			graph[b].push_back(a);
			
			q.merg(a, b);
		}
	}
	
	memset(dis, -1, sizeof dis);
	for (int i = 1; i <= n; i++) {
		if (dis[i] == -1) dfs(i, 0);
	}
	return 0;
}

Compilation message

pipes.cpp: In function 'int main()':
pipes.cpp:69:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   69 |  scanf("%d%d", &n, &m);
      |  ~~~~~^~~~~~~~~~~~~~~~
pipes.cpp:72:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   72 |   scanf("%d%d", &a, &b);
      |   ~~~~~^~~~~~~~~~~~~~~~

Subtask #1
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 3788 KB Output is correct
2 Correct 4 ms 3788 KB Output is correct

Subtask #2
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 4264 KB Output is correct
2 Correct 7 ms 4040 KB Output is correct

Subtask #3
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 134 ms 4064 KB Output is correct
2 Correct 130 ms 3908 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 232 ms 4704 KB Output is correct
2 Correct 267 ms 4772 KB Output is correct

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 399 ms 6164 KB Output is correct
2 Correct 382 ms 5676 KB Output is correct

Subtask #6
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 513 ms 10852 KB Output is correct
2 Correct 483 ms 7472 KB Output is correct

Subtask #7
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 768 ms 11960 KB Output is correct
2 Correct 797 ms 9096 KB Output is correct

Subtask #8
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 1027 ms 13892 KB Output is correct
2 Correct 982 ms 8972 KB Output is correct

Subtask #9
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 1261 ms 13952 KB Output is correct
2 Correct 1223 ms 8964 KB Output is correct

Subtask #10
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 1619 ms 13352 KB Output is correct
2 Correct 1572 ms 10524 KB Output is correct