dfs判断联通块

#include <iostream>
#include <cstring>
#include <algorithm>

using namespace std;

#define int long long
#define INF 0x3f3f3f3f

const int N = 1e5 + 10, M = 2e5 + 10;

int n, m;
int h[N], e[M], ne[M], idx;
bool st[N];
int x1, y1, x2, y2;
vector<pair<int, int>> pos;

void add(int a, int b) // 添加一条边a->b
{
    e[idx] = b, ne[idx] = h[a], h[a] = idx++;
}

void dfs(int u)
{
    st[u] = true;
    x1 = min(x1, pos[u].first);
    x2 = max(x2, pos[u].first);
    y1 = min(y1, pos[u].second);
    y2 = max(y2, pos[u].second);
    for (int i = h[u]; ~i; i = ne[i])
    {
        int j = e[i];
        if (!st[j])
            dfs(j);
    }
}

signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);

    memset(h, -1, sizeof(h));

    cin >> n >> m;
    pos.push_back({0, 0}); // 优化
    for (int i = 1; i <= n; ++i)
    {
        int x, y;
        cin >> x >> y;
        pos.push_back({x, y});
    }
    while (m--)
    {
        int a, b;
        cin >> a >> b;
        add(a, b), add(b, a);
    }

    int res = INF;
    for (int i = 1; i <= n; ++i)
    {
        if (!st[i])
        {
            x1 = INF, y1 = INF, x2 = 0, y2 = 0;
            dfs(i);
            res = min((x2 - x1) * 2 + (y2 - y1) * 2, res);
        }
    }
    cout << res << endl;

    return 0;
}