Kosaraju(求强连通分量，缩点，求缩点后联通块的入度).md

tags	title	created	modified
Code	Kosaraju(求强连通分量，缩点，求缩点后联通块的入度)	2022-09-02T13:14:01.901Z	2022-09-02T13:14:25.162Z

Kosaraju(求强连通分量，缩点，求缩点后联通块的入度)

// Kosaraju
#include <bits/stdc++.h>

using namespace std;

const int inf = 0x3f3f3f3f;
const int maxn = 1e5 + 7;
int V;
int cost[maxn], vis[maxn], group[maxn], in[maxn];
int mincost[maxn];
vector<int> G[maxn];
vector<int> rG[maxn];
vector<int> q;
vector<int> sG[maxn];

void add(int from, int to)
{
    G[from].push_back(to);
    rG[to].push_back(from);
}

void dfs1(int v)
{
    vis[v] = true;
    for (int i = 0; i < (int)G[v].size(); ++i)
        if (!vis[G[v][i]])
            dfs1(G[v][i]);
    q.push_back(v);
}

void dfs2(int v, int k)
{
    vis[v] = true;
    group[v] = k;
    for (int i = 0; i < (int)rG[v].size(); ++i)
        if (!vis[rG[v][i]])
            dfs2(rG[v][i], k);
}

int scc()
{
    memset(vis, 0, sizeof(vis));
    q.clear();
    for (int i = 0; i < V; ++i)
        if (!vis[i])
            dfs1(i);

    int k = 0;
    memset(vis, 0, sizeof(vis));
    for (int i = q.size() - 1; i >= 0; --i)
        if (!vis[q[i]])
            dfs2(q[i], k++);
    return k;
}
void build()
{
    memset(in, 0, sizeof(in));

    for (int v = 0; v < V; ++v)
    {
        for (int i = 0; i < (int)G[v].size(); ++i)
        {
            if (group[v] == group[G[v][i]])
                continue;
            sG[v].push_back(G[v][i]);
            in[group[G[v][i]]]++;
        }
    }
}
void init()
{
    for (int i = 0; i < V; ++i)
    {
        G[i].clear();
        rG[i].clear();
        sG[i].clear();
    }
}
int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    int n, m;
    while (cin >> n >> m)
    {
        V = n;
        int x, y;
        for (int i = 0; i < V; ++i)
            cin >> cost[i];
        init();
        for (int i = 0; i < m; ++i)
        {
            cin >> x >> y;
            add(x - 1, y - 1);
        }

        memset(mincost, inf, sizeof(mincost));
        int N = scc();
        for (int i = 0; i < V; ++i)
            mincost[group[i]] = min(mincost[group[i]], cost[i]);
        build();
        int sum = 0, ct = 0;
        for (int i = 0; i < N; ++i)
        {
            if (in[i] == 0)
            {
                ct++;
                sum += mincost[i];
            }
        }
        cout << ct << " " << sum << endl;
    }
    return 0;
}