Submission #37478

#	Time	Username	Problem	Language	Result	Execution time	Memory
37478		mohammad_kilani	Pipes (CEOI15_pipes)	C++14	100 / 100	1361 ms	8852 KiB

pipes

#include <bits/stdc++.h>
using namespace std;
#define mod 1000000007
#define oo 2000000000
const int N = 100010;
int n, m , cnt = 0 , dsu[N] , dsu2[N] , comp[N] , u , v , a ,b , depth[N] , qu[N], st , en, node;
bitset < N > bridge;
vector< pair<int,int> > g[N];
pair<int,int> parent[N];

inline int find(int u){ return (u == dsu[u] ? u : dsu[u] = find(dsu[u]));}
inline int find2(int u){ return (u == dsu2[u] ? u : dsu2[u] = find2(dsu2[u]));}

inline int get(int node1,int node2){
	if(node1 == node2) return find2(node1);
	if(depth[node1] > depth[node2]){
		bridge[parent[node1].second] = false;
		return dsu2[node1] = dsu2[node2] = get(find2(parent[node1].first),node2);
	}
	bridge[parent[node2].second] = false;
	return dsu2[node1] = dsu2[node2] = get(node1,find2(parent[node2].first));
}

int main() {
	scanf("%d%d",&n,&m);
	for(int i=1;i<=n;i++) dsu[i] = dsu2[i] = i , comp[i] = 1;
	for(int i=0;i<m;i++){
		scanf("%d%d",&u,&v);
		a = find(u);
		b = find(v);
		if(a == b){
			get(find2(u),find2(v));
		}
		else{
			g[u].push_back(make_pair(v,cnt));
			g[v].push_back(make_pair(u,cnt));
			bridge[cnt] = true;
			if(comp[a] > comp[b]){swap(a,b);swap(u,v);}
			st = 0 , en = 1;
			qu[0] = u;
			parent[u] = make_pair(v,cnt);
			depth[u] = depth[v] + 1;
			dsu2[u] = u;
			while(st < en){
				node = qu[st++];
				for(int i=0;i<g[node].size();i++){
					if(g[node][i].first != parent[node].first){
						qu[en++] = g[node][i].first;
						parent[g[node][i].first] = make_pair(node,g[node][i].second);
						depth[g[node][i].first] = depth[node] + 1;
						if(bridge[g[node][i].second]) dsu2[g[node][i].first] = g[node][i].first; else dsu2[g[node][i].first] = find2(dsu2[node]);
					}
				}
			}
			comp[b] += comp[a];
			comp[a] = 0;
			dsu[a] = b;
			cnt++;
		}
	}
	for(int i=1;i<=n;i++){
		for(int j=0;j<g[i].size();j++){
			if(i > g[i][j].first || !bridge[g[i][j].second]) continue;
			printf("%d %d\n",i,g[i][j].first);
		}
	}
	return 0;
}

Compilation message (stderr)

pipes.cpp: In function 'int main()':
pipes.cpp:46:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<g[node].size();i++){
                 ~^~~~~~~~~~~~~~~
pipes.cpp:62:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=0;j<g[i].size();j++){
               ~^~~~~~~~~~~~
pipes.cpp:25:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d",&n,&m);
  ~~~~~^~~~~~~~~~~~~~
pipes.cpp:28:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d",&u,&v);
   ~~~~~^~~~~~~~~~~~~~

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