Submission #656937

#	Time	Username	Problem	Language	Result	Execution time	Memory
656937		benjaminkleyn	Pipes (CEOI15_pipes)	C++17	40 / 100	169 ms	17140 KiB

pipes

#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2")
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

const int max_n = 100000;

int mem[2 * max_n];

int find(int u, int dsu)
{
    return (mem[max_n * dsu + u] == u ? u : mem[max_n * dsu + u] = find(mem[max_n * dsu + u], dsu));
}

bool same_set(int u, int v, int dsu)
{
    return find(u, dsu) == find(v, dsu);
}

void unite(int u, int v, int dsu)
{
    mem[max_n * dsu + v] = find(u, dsu);
}


int n, m, timer = 0;
vector<int> g[max_n];
int edge_xor[2 * max_n], edge_cnt = 0;

void dfs(int u, int p = -1)
{
    mem[u] = mem[max_n + u] = ++timer;
    for (int e : g[u])
        if (e != p)
        {
            int v = edge_xor[e] ^ u;
            if (mem[v])
                mem[max_n + u] = min(mem[max_n + u], mem[v]);
            else
            {
                dfs(v, e);
                mem[max_n + u] = min(mem[max_n + u], mem[max_n + v]);

                if (mem[max_n + v] > mem[u])
                    cout << u + 1 << ' ' << v + 1 << '\n';
            }
        }
}


int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    cin >> n >> m;

    for (int i = 0; i < n; i++)
        mem[i] = mem[max_n + i] = i;
    
    for (int i = 0, a ,b; i < m; i++)
    {
        cin >> a >> b;
        a--, b--;

        if (!same_set(a, b, 0))
            unite(a, b, 0);
        else if (!same_set(a, b, 1))
            unite(a, b, 1);
        else continue;

        g[a].push_back(edge_cnt);
        g[b].push_back(edge_cnt);
        edge_xor[edge_cnt] = a ^ b;
        edge_cnt++;
    }

    for (int i = 0; i < n; i++)
        mem[i] = mem[max_n + i] = 0;

    for (int i = 0; i < n; i++)
        if (!mem[i])
            dfs(i);

    return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 10 / 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