Submission #81943

#	Time	Username	Problem	Language	Result	Execution time	Memory
81943		Saboon	Pipes (CEOI15_pipes)	C++14	80 / 100	5085 ms	15856 KiB

pipes

#include <iostream>
#include <queue>
#include <stack>
#include <vector>
#include <cstring>
#include <cmath>
#include <map>
#include <unordered_map>
#include <set>
#include <algorithm>
#include <iomanip>
#define F first
#define S second
#define PB push_back
#define PF push_front
#define MP make_pair
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
const int maxn = 1e5 + 10;
const ll inf = 1e18 + 1000;

int h[maxn], par[maxn][22], dp[maxn];
bool cut[maxn];

int lca (int v, int u) {
    if (h[v] < h[u])
        swap (v, u);
    for (int i = 20; i >= 0; i--)
        if (h[v] - (1 << i) >= h[u])
            v = par[v][i];
    if (v == u)
        return v;
    for (int i = 20; i >= 0; i--) {
        if (par[v][i] != par[u][i]) {
            v = par[v][i];
            u = par[u][i];
        }
    }
    return par[v][0];
}

vector <int> g[maxn];

void dfs2 (int v, int p) {
    dp[v] = h[v];
    for (auto w : g[v]) {
        if (w != p) {
            h[w] = h[v] + 1;
            dfs2 (w, v);
        }
    }
}

void dfs1 (int v, int p) {
    par[v][0] = p;
    for (int i = 1; i <= 20; i++) {
        if (par[v][i - 1] != -1)
            par[v][i] = par[par[v][i - 1]][i - 1];
        else
            par[v][i] = -1;
    }
    for (auto u : g[v]) {
        if (u != p) {
            dfs1 (u, v);
        if (h[v] > h[u])
            cut[u] = cut[v];
        }
    }
}

void dfs (int v, int p = -1) {
    for (auto w : g[v]) {
        if (w != p) {
            dfs (w, v);
            dp[v] = min (dp[v], dp[w]);
        }
    }
    cut[v] &= (h[v] <= dp[v]);
}

int dpar[maxn];
int get_par (int v) {
    if (dpar[v] < 0)
        return v;
    return dpar[v] = get_par (dpar[v]);
}

int n;
void merge (int v, int u) {
    int vpar = get_par (v);
    dfs (vpar);
    dfs1 (v, u);
    cut[v] = 1;
    h[v] = h[u] + 1;
    dfs2 (v, u);
    dpar[get_par(u)] += dpar[get_par(v)];
    dpar[get_par(v)] = get_par(u);
}

bool mark[maxn];

int main() {
    memset (par, -1, sizeof par);
    memset (dpar, -1, sizeof dpar);
    int m;
    cin >> n >> m;
    while (m --) {
        int v, u;
        cin >> v >> u;
        int vpar = get_par(v), upar = get_par(u);
        if (vpar != upar) {
            if (dpar[vpar] < dpar[upar])
                swap (v, u);
            merge (v, u);
            g[u].PB (v);
            g[v].PB (u);
        }
        else {
            int w = lca (v, u);
            dp[v] = min (dp[v], h[w]);
            dp[u] = min (dp[u], h[w]);
        }
    }
    for (int i = 1; i <= n; i++) {
        int v = get_par (i);
        if (!mark[v]) {
            mark[v] = 1;
            dfs (v);
        }
    }
    for (int i = 1; i <= n; i++)
        if (cut[i])
            cout << i << " " << par[i][0] << endl;
}

• 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: 0 / 10
• Subtask 10: 0 / 10