Submission #804597

#	Time	Username	Problem	Language	Result	Execution time	Memory
804597		Hanksburger	Pipes (CEOI15_pipes)	C++17	90 / 100	797 ms	23268 KiB

pipes

#include <bits/stdc++.h>
using namespace std;
vector<int> adj[100005];
int par[100005][2], t;
int findPar(int u, int x)
{
    return (par[u][x]==u?u:par[u][x]=findPar(par[u][x], x));
}
void dfs(int u, int p)
{
    par[u][0]=par[u][1]=(++t);
    int pass=1;
    for (int v:adj[u])
    {
        if (v==p && pass)
        {
            pass=0;
            continue;
        }
        if (par[v][0])
            par[u][1]=min(par[u][1], par[v][0]);
        else
        {
            dfs(v, u);
            par[u][1]=min(par[u][1], par[v][1]);
            if (par[v][1]>=par[v][0])
                cout << u << ' ' << v << '\n';
        }
    }
}
int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int n, m;
    cin >> n >> m;
    for (int i=1; i<=n; i++)
        par[i][0]=par[i][1]=i;
    for (int i=1; i<=m; i++)
    {
        int u, v, U, V;
        cin >> u >> v;
        if (findPar(u, 0)!=findPar(v, 0))
        {
            par[par[u][0]][0]=par[v][0];
            adj[u].push_back(v);
            adj[v].push_back(u);
        }
        else if (findPar(u, 1)!=findPar(v, 1))
        {
            par[par[u][1]][1]=par[v][1];
            adj[u].push_back(v);
            adj[v].push_back(u);
        }
    }
    for (int i=1; i<=n; i++)
        par[i][0]=par[i][1]=0;
    for (int i=1; i<=n; i++)
        if (!par[i][0])
            dfs(i, 0);
}

Compilation message (stderr)

pipes.cpp: In function 'int main()':
pipes.cpp:42:19: warning: unused variable 'U' [-Wunused-variable]
   42 |         int u, v, U, V;
      |                   ^
pipes.cpp:42:22: warning: unused variable 'V' [-Wunused-variable]
   42 |         int u, v, 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: 0 / 10