Submission #1004703

#	Time	Username	Problem	Language	Result	Execution time	Memory
1004703		Valaki2	Pipes (CEOI15_pipes)	C++14	100 / 100	855 ms	15820 KiB

pipes

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

#define pb push_back

const int maxn = 2e5;

int n, m;
vector<int> graph[1 + maxn];

int par[1 + maxn];
int sz[1 + maxn];

int par2[1 + maxn];
int sz2[1 + maxn];

void make_set2(int a) {
    par2[a] = a;
    sz2[a] = 1;
}

int find_set2(int a) {
    if(a == par2[a]) {
        return a;
    }
    return par2[a] = find_set2(par2[a]);
}

/*void union_sets2(int a, int b) {
    a = find_set2(a), b = find_set2(b);
    if(a == b) {
        return;
    }
    if(sz2[a] < sz2[b]) {
        swap(a, b);
    }
    par2[b] = a;
    sz2[a] += sz2[b];
}*/

void make_set(int a) {
    par[a] = a;
    sz[a] = 1;
}

/*int find_set(int a) {
    if(a == par[a]) {
        return a;
    }
    return par[a] = find_set(par[a]);
}

void union_sets(int a, int b) {
    int ax = a, bx = b;
    a = find_set(a), b = find_set(b);
    if(a == b) {
        union_sets2(ax, bx);
        return;
    }
    graph[ax].pb(bx);
    graph[bx].pb(ax);
    if(sz[a] < sz[b]) {
        swap(a, b);
    }
    par[b] = a;
    sz[a] += sz[b];
}*/

bool vis[1 + maxn];
int l[1 + maxn];
int d[1 + maxn];
int parent[1 + maxn];
int timer;

void dfs(const int &cur) {
    timer++;
    l[cur] = d[cur] = timer;
    vis[cur] = true;
    for(const int &nei : graph[cur]) {
        if(nei == parent[cur]) {
            continue;
        }
        if(vis[nei]) {
            l[cur] = min(l[cur], d[nei]);
        } else {
            parent[nei] = cur;
            dfs(nei);
            l[cur] = min(l[cur], l[nei]);
            if(l[nei] > d[cur] && cur <= n && nei <= n) {
                cout << cur << " " << nei << "\n";
            }
        }
    }
}

void solve() {
    cin >> n >> m;
    int x, y;
    for(int i = 1; i <= n; i++) {
        make_set(i);
    }
    for(int i = 1; i <= n; i++) {
        make_set2(i);
    }
    int a, b;
    for(int i = 1; i <= m; i++) {
        cin >> x >> y;
        //union_sets(x, y);
        a = x, b = y;
        while(par[a] != a) {
            a = par[a];
        }
        while(par[b] != b) {
            b = par[b];
        }
        if(a == b) {
            a = x, b = y;
            while(par2[a] != a) {
                a = par2[a];
            }
            while(par2[b] != b) {
                b = par2[b];
            }
            if(a == b) {
                // -
            } else {
                if(sz2[a] < sz2[b]) {
                    swap(a, b);
                }
                par2[b] = a;
                sz2[a] += sz2[b];
            }
        } else {
            graph[x].pb(y);
            graph[y].pb(x);
            if(sz[a] < sz[b]) {
                swap(a, b);
            }
            par[b] = a;
            sz[a] += sz[b];
        }
    }
    for(int i = 1; i <= n; i++) {
        int j = find_set2(i) + n;
        graph[i].pb(j);
        graph[j].pb(i);
    }
    for(int i = 1; i <= 2 * n; i++) {
        if(!vis[i]) {
            dfs(i);
        }
    }
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    solve();
}

• 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