POJ1144 tarjan求割点模板

Posted 2021-08-20 hesorchen

输入恶心人的远古题好恶心。
POJ的评测机好拉，每次写完CE CE CE。

题目

POJ 1144

割点板子题。

代码

#include <iostream>//CE *1
#include <cstdio>//CE *1
#include <string>//CE *1
#include <vector>//CE *1
using namespace std;

const int N = 1e5 + 5;
vector<int> edge[N];

vector<int> f(string a)
{
    vector<int> res;
    a += ' ';
    int sum = 0;
    // for (auto it : a)//CE *1
    for (int i = 0; i < a.size(); i++)
    {
        char it = a[i];
        if (it == ' ')
            res.push_back(sum), sum = 0;
        else
            sum = sum * 10 + (it - '0');
    }
    return res;
}

int dfn[N], low[N], ct;
int ans;
void tarjan(int u, bool isroot)
{
    int tot = 0;
    dfn[u] = low[u] = ++ct;
    // for (auto v : edge[u])//CE *1
    for (int i = 0; i < edge[u].size(); i++)
    {
        int v = edge[u][i];
        if (!dfn[v])
        {
            tarjan(v, 0);
            low[u] = min(low[u], low[v]);
            if (low[v] >= dfn[u])
                ++tot;
        }
        else
            low[u] = min(low[u], dfn[v]);
    }
    if ((isroot && tot >= 2) || (!isroot && tot >= 1))
        ++ans;
}
int main()
{
    int n;
    while (cin >> n, n)
    {
        for (int i = 0; i <= n; i++)
            edge[i].clear(), dfn[i] = 0;
        ans = ct = 0;
        string a;
        while (getline(cin, a), a[0] != '0')
        {
            vector<int> temp = f(a);
            int m = temp.size();
            for (int i = 1; i < m; i++)
            {
                edge[temp[0]].push_back(temp[i]);
                edge[temp[i]].push_back(temp[0]);
            }
        }
        tarjan(1, 1);
        cout << ans << endl;
    }
    return 0;
}

/*
*/