제출 #484787

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
484787		Victor	Pipes (CEOI15_pipes)	C++17	0 / 100	220 ms	15404 KiB

pipes

#include <bits/stdc++.h>

using namespace std;

#define rep(i, a, b) for (int i = (a); i < (b); ++i)
#define per(i, a, b) for (int i = (b - 1); i >= (a); --i)
#define trav(a, x) for (auto &a : x)

#define all(x) x.begin(), x.end()
#define sz(x) x.size()
#define pb push_back
#define debug(x) cout << #x << " = " << x << endl

#define umap unordered_map
#define uset unordered_set

typedef pair<int, int> ii;
typedef pair<int, ii> iii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<vi> vvi;

typedef long long ll;
typedef pair<ll, ll> pll;
typedef vector<ll> vll;
typedef vector<pll> vpll;

const int INF = 1'000'000'007;

struct union_find {
    int p[100001];
    char rank[100001];
    union_find(int n) {
        rep(i, 0, n) p[i] = i;
        memset(rank, 0, n * 4);
    }

    int find_set(int i) { return p[i] == i ? i : p[i] = find_set(p[i]); }
    bool same(int i,int j) {return find_set(i)==find_set(j);}
    void union_set(int i, int j) {
        i = find_set(i);
        j = find_set(j);
        if (i == j) return;

        if (rank[i] < rank[j]) swap(i, j);
        if (rank[i] == rank[j]) ++rank[i];
        p[j] = i;
    }
};

int dfs_p[100001], dfs_num[100001], dfs_lo[100001], cnt = 0;
vi graph[100001];

void dfs(int u) {
    dfs_num[u] = dfs_lo[u] = cnt++;
    trav(v, graph[u]) if (v != dfs_p[u]) {

        if (dfs_num[v] == -1) {
            dfs_p[v] = u;
            dfs(v);
            if (dfs_num[u] < dfs_lo[v]) cout << u + 1 << ' ' << v + 1 << endl;
            dfs_lo[u] = min(dfs_lo[u], dfs_lo[v]);
        }

        else
            dfs_lo[u] = min(dfs_lo[u], dfs_num[v]);
    }
}

int main() {
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit);

    memset(dfs_num, -1, sizeof(dfs_num));
    int n, m, u, v;
    cin >> n >> m;
    union_find uf1(n), uf2(n);

    rep(i, 0, m) {
        cin >> u >> v;
        --u;
        --v;
        
        if(uf1.same(u,v))if(!uf2.same(u,v)){
            uf2.union_set(u,v);
            graph[u].pb(v);
            graph[v].pb(u);
        }

        else {
            uf2.union_set(u,v);
            graph[u].pb(v);
            graph[v].pb(u);
        }
    }

    rep(i, 0, n) {
        if (dfs_num[i] != -1) continue;
        cnt = 0;
        dfs_p[i] = i;
        dfs(i);
    }
    return 0;
}

컴파일 시 표준 에러 (stderr) 메시지

pipes.cpp: In function 'int main()':
pipes.cpp:84:11: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
   84 |         if(uf1.same(u,v))if(!uf2.same(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