Submission #872690

#	Time	Username	Problem	Language	Result	Execution time	Memory
872690		Ghulam_Junaid	Pipes (CEOI15_pipes)	C++17	0 / 100	912 ms	65536 KiB

pipes

#include <bits/stdc++.h>
using namespace std;

const int N = 1e5 + 10;
int par1[N], par2[N], h[N], mnh[N];
bool vis[N];
vector<int> g[N];
vector<pair<int, int>> bridges;

int root1(int v){
    return (par1[v] == -1 ? v : par1[v] = root1(par1[v]));
}

int root2(int v){
    return (par2[v] == -1 ? v : par2[v] = root2(par2[v]));
}

void merge1(int u, int v){    
    int r1 = root1(v);
    int r2 = root1(u);

    par1[r1] = r2;

    g[v].push_back(u);
    g[u].push_back(v);
}

void merge2(int u, int v){
    int r1 = root2(u);
    int r2 = root2(v);

    if (r1 == r2)
        return;

    par2[r1] = r2;

    g[v].push_back(u);
    g[u].push_back(v);
}

void dfs(int v, int p = -1){
    vis[v] = 1;
    mnh[v] = h[v];
    for (int u : g[v]){
        if (vis[u]){
            if (u != p)
                mnh[v] = min(mnh[v], h[u]);
            continue;
        }

        h[u] = h[v] + 1;
        dfs(u, v);
        mnh[v] = min(mnh[v], mnh[u]);

        if (mnh[u] >= h[u])
            bridges.push_back({u, v});
    }
}

int main(){
    int n, m;
    scanf("%d%d", &n, &m);

    for (int i=1; i<=n; i++)
        par1[i] = par2[i] = -1;

    for (int i=0; i<m; i++){
        int u, v;
        scanf("%d%d", &u, &v);

        if (root1(u) == root1(v))
            merge2(u, v);
        else
            merge1(u, v);
    }

    for (int v = 1; v <= n; v++)
        if (!vis[v])
            dfs(v);

    for (auto [u, v] : bridges)
        printf("%d %d\n", u, v);
}

Compilation message (stderr)

pipes.cpp: In function 'int main()':
pipes.cpp:62:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   62 |     scanf("%d%d", &n, &m);
      |     ~~~~~^~~~~~~~~~~~~~~~
pipes.cpp:69:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   69 |         scanf("%d%d", &u, &v);
      |         ~~~~~^~~~~~~~~~~~~~~~

• 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