Submission #146323

#	Time	Username	Problem	Language	Result	Execution time	Memory
146323		evpipis	Pipes (CEOI15_pipes)	C++98	100 / 100	1908 ms	15972 KiB

pipes

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

#define fi first
#define se second
#define pb push_back
#define mp make_pair
typedef pair<int, int> ii;

const int len = 1e5+3;
int n, m, cnt;
int par[len], num[len], low[len];
vector<ii> adj[len], vec;

struct dsu{
    int anc[len];

    void init(){
        for (int i = 1; i <= n; i++)
            anc[i] = i;
    }

    int fin(int i){
        if (anc[i] == i) return i;
        return anc[i] = fin(anc[i]);
    }

    void join(int i, int j){
        i = fin(i), j = fin(j);
        if (i != j)
            anc[j] = i;
    }
};

dsu one, two;

void dfs(int u){
    num[u] = low[u] = ++cnt;
    for (int j = 0; j < adj[u].size(); j++){
        ii v = adj[u][j];
        if (!num[v.fi]){
            par[v.fi] = v.se;
            dfs(v.fi);

            if (low[v.fi] > num[u])
                printf("%d %d\n", u, v.fi);
            low[u] = min(low[u], low[v.fi]);
        }
        else if (v.se != par[u]){
            low[u] = min(low[u], num[v.fi]);
        }
    }
}

int main(){
    scanf("%d %d", &n, &m);
    one.init();
    two.init();
    for (int i = 0; i < m; i++){
        int a, b;
        scanf("%d %d", &a, &b);
        if (one.fin(a) != one.fin(b)){
            vec.pb(mp(a, b));
            one.join(a, b);
        }
        else if (two.fin(a) != two.fin(b)){
            vec.pb(mp(a, b));
            two.join(a, b);
        }
    }

    for (int i = 0; i < vec.size(); i++){
        int a = vec[i].fi, b = vec[i].se;
        adj[a].pb(mp(b, i+1));
        adj[b].pb(mp(a, i+1));
    }

    for (int i = 1; i <= n; i++)
        if (!num[i])
            dfs(i);
    return 0;
}

Compilation message (stderr)

pipes.cpp: In function 'void dfs(int)':
pipes.cpp:39:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int j = 0; j < adj[u].size(); j++){
                     ~~^~~~~~~~~~~~~~~
pipes.cpp: In function 'int main()':
pipes.cpp:72:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < vec.size(); i++){
                     ~~^~~~~~~~~~~~
pipes.cpp:56:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d", &n, &m);
     ~~~~~^~~~~~~~~~~~~~~~~
pipes.cpp:61:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d", &a, &b);
         ~~~~~^~~~~~~~~~~~~~~~~

• 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: 10 / 10