Submission #1026988

#	Time	Username	Problem	Language	Result	Execution time	Memory
1026988		vjudge1	Pipes (CEOI15_pipes)	C++17	0 / 100	633 ms	7540 KiB

pipes

#include <bits/stdc++.h>

#define ll long long
using namespace std;
const int N = 1e5;
vector < int > adj[N + 2];
struct dsu{
    int par[N + 2];
    int find_par(const int &u){
        if(par[u] < 0)return u;
        par[u] = find_par(par[u]);
        return par[u];
    }
    bool union_set(int u , int v){
        u = find_par(u);
        v = find_par(v);
        if(u != v){
            if(par[u] > par[v])swap(u , v);
            par[u] += par[v];
            par[v] = u;
            return true;
        }
        return false;
    }

} par1 , par2;
int timer = 0;
void dfs(int &u , int &p){
    par1.par[u] = par2.par[u] = ++timer;
    for(int &v:adj[u]){
        if(v == p) continue;
        if(!par2.par[v]){
            dfs(v , u);
            par1.par[u] = min(par1.par[u] , par1.par[v]);
            if(par1.par[v] > par2.par[u]){
                cout << u << " " << v <<'\n';
            } 
        }
        else par1.par[u] = min(par1.par[u] , par2.par[v]);

    }
}
void solve() {
    int n , m;
    cin >> n >> m;
    for(int i = 1; i <= n; i++){
        par1.par[i] = par2.par[i] = -1;
    }
    for(int i = 1; i <= m ;i ++){
        int u , v;
        cin >> u >> v;
        if(par1.union_set(u , v)){
            adj[u].push_back(v);
            adj[v].push_back(u);
        }
        else if(par2.union_set(u , v)){
            adj[u].push_back(v);
            adj[v].push_back(u);
        }
    }
    for(int  i = 1; i <= n ; i ++){
        par1.par[i] = par1.par[i] = 0;
    }
    for(int i = 1; i <= n ; i++){
        if(!par2.par[i])dfs(i , i);
    }
    
}

signed main() {
    ios::sync_with_stdio(0), cin.tie(0);
    
    #define _ "maxseq."
    if (fopen(_ "inp", "r")) {
        freopen(_ "inp", "r", stdin);
        freopen(_ "out", "w", stdout);
    }
    
    solve();
}

Compilation message (stderr)

pipes.cpp: In function 'void solve()':
pipes.cpp:62:21: warning: operation on 'par1.dsu::par[i]' may be undefined [-Wsequence-point]
   62 |         par1.par[i] = par1.par[i] = 0;
      |         ~~~~~~~~~~~~^~~~~~~~~~~~~~~~~
pipes.cpp: In function 'int main()':
pipes.cpp:75:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   75 |         freopen(_ "inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~
pipes.cpp:76:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   76 |         freopen(_ "out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

• 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