Submission #460891

#	Time	Username	Problem	Language	Result	Execution time	Memory
460891		kingfran1907	Pipes (CEOI15_pipes)	C++14	0 / 100	1500 ms	23436 KiB

pipes

#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 dep[maxn];

int dfs(int x, int parr) {
	int out = 0;
	dep[x] = 1 + dep[parr];
	for (int tren : graph[x]) {
		if (tren == parr) continue; 
		if (dep[tren] == -1) {
			int kol = dfs(tren, x);
			if (kol == 0) {
				printf("%d %d\n", tren, x);
			}
			out = max(out, kol - 1);
		} else {
			int dis = dep[x] - dep[tren];
			out = max(out, dis);
		}
	}
	return out;
}

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 (q.fin(a) != q.fin(b)) {
			graph[a].push_back(b);
			graph[b].push_back(a);
			
			if (p.fin(a) != p.fin(b)) p.merg(a, b);
			else q.merg(a, b);
		}
	}
	
	memset(dep, -1, sizeof dep);
	dep[0] = 0;
	for (int i = 1; i <= n; i++) {
		if (dep[i] == -1) dfs(i, 0);
	}
	return 0;
}

Compilation message (stderr)

pipes.cpp: In function 'int main()':
pipes.cpp:65:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   65 |  scanf("%d%d", &n, &m);
      |  ~~~~~^~~~~~~~~~~~~~~~
pipes.cpp:68:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   68 |   scanf("%d%d", &a, &b);
      |   ~~~~~^~~~~~~~~~~~~~~~

• Subtask 1: 0 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 10
• Subtask 4: 0 / 10
• Subtask 5: 0 / 10
• Subtask 6: 0 / 10
• Subtask 7: 0 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 10
• Subtask 10: 0 / 10