Submission #100496

#	Time	Username	Problem	Language	Result	Execution time	Memory
100496		doowey	Pipes (CEOI15_pipes)	C++14	20 / 100	1135 ms	14840 KiB

pipes

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;

#define fi first
#define se second
#define mp make_pair
#define fastIO ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

const int N = (int)1e5 + 9;

struct DSU{
    int pi[N];
    int sz[N];
    int fin(int x){
        if(pi[x] == x)
            return x;
        return pi[x] = fin(pi[x]);
    }
    bool unite(int a, int b){
        a = fin(a);
        b = fin(b);
        if(a==b)
            return false;
        if(sz[a] > sz[b])
            swap(a, b);
        sz[b] += sz[a];
        pi[a] = b;
        return true;
    }
    void Init(){
        for(int i = 0 ;i  < N ; i ++ ){
            pi[i] = i;
            sz[i] = 1;
        }
    }
};

DSU A, B;

vector<int> T[N];

vector<pii> answ;

int tin[N];
int low[N];
int timer;

bool vis[N];

void bridge(int a, int b){
    if(a>b)
        swap(a, b);
    answ.push_back(mp(a,b));
}

void dfs(int node, int par){
    if(vis[node]){
        return;
    }
    vis[node] = true;
    tin[node] = timer ++ ;
    low[node] = tin[node];
    for(auto x : T[node]){
        if(x == par){
            continue;
        }
        if(vis[x]){
            low[node] = min(low[node], tin[x]);
        }
        else{
            dfs(x, node);
            low[node] = min(low[node], low[x]);
            if(tin[node] < low[x]){
                bridge(node, x);
            }
        }
    }
}



int main(){
    fastIO;
    A.Init();
    B.Init();
    int n, m;
    cin >> n >> m;
    int u, v;
    for(int i = 0 ; i < m ; i ++ ){
        cin >> u >> v;
        if(A.unite(u, v)){
            T[u].push_back(v);
            T[v].push_back(u);
        }
        else if(B.unite(u, v)){
            T[u].push_back(v);
            T[v].push_back(u);
        }
    }
    for(int i = 1; i <= n; i ++ )
        dfs(i,-1);
    bool ok;
    sort(answ.begin(), answ.end());
    for(int i = 0 ;i < answ.size(); i ++ ){
        ok = true;
        if(i>0)
            if(answ[i]==answ[i-1])ok = false;
        if(i+1<answ.size())
            if(answ[i]==answ[i+1])ok = false;
        if(ok)
            cout << answ[i].fi << " " << answ[i].se << "\n";
    }
    return 0;
}

Compilation message (stderr)

pipes.cpp: In function 'int main()':
pipes.cpp:108:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0 ;i < answ.size(); i ++ ){
                    ~~^~~~~~~~~~~~~
pipes.cpp:112:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         if(i+1<answ.size())
            ~~~^~~~~~~~~~~~

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