【Codeforces 427C】Checkposts

【链接】 我是链接,点我呀:)

【题意】

环里面的点只需要一个点就能全都保护
问你最少需要多少花费以及最少的点才能将所有的点都保护

【题解】

有向图的强连通分量求出所有的联通分量
显然每个联通分量里面只需选择最小那个点就好
如果有多个最小的点,那么这个环就有多个选择。
每个环的最小点个数连乘一下就是方案数了
然后每个联通分量的最小值再全部都加起来就ok

【代码】

import java.io.*;
import java.util.*;

public class Main {

    static InputReader in;
    static PrintWriter out;

    public static void main(String[] args) throws IOException{
        //InputStream ins = new FileInputStream("E:\\rush.txt");
        InputStream ins = System.in;
        in = new InputReader(ins);
        out = new PrintWriter(System.out);
        //code start from here
        new Task().solve(in, out);
        out.close();
    }

    static int N = (int)1e5;
    static class Task{
        int n,m;
        ArrayList g[] = new ArrayList[N+10],g1[] = new ArrayList[N+10];
        int cost[] = new int[N+10];
        int dfn[] = new int[N+10],low[] = new int[N+10];
        boolean in[] = new boolean[N+10];
        int mystack[] = new int[N+10];
        int tot = 0,top = 0,totn = 0;

        void dfs(int x) {
        	dfn[x] = low[x] = ++tot;
        	mystack[++top] = x;
        	in[x] = true;
        	int len = g[x].size();
        	for (int i = 0;i < len;i++) {
        		int y = (int)g[x].get(i);
        		if (dfn[y]==0) {
        			dfs(y);
        			low[x] = Math.min(low[x],low[y]);
        		}else
        			if (in[y] && dfn[y]<low[x]){
        				low[x] = dfn[y];
        			}
        	}
        	if (low[x]==dfn[x]) {
        		int v = 0;
        		totn++;
        		while (v!=x) {
        			v = mystack[top];
        			in[v] = false;
        			g1[totn].add(v);
        			top--;
        		}
        	}
        }

        public void solve(InputReader in,PrintWriter out) {
        	for (int i = 1;i <= N;i++) {
        		g[i] = new ArrayList();
        		g1[i] = new ArrayList();
        	}
        	n = in.nextInt();
        	for (int i = 1;i <= n;i++) cost[i] = in.nextInt();
        	m = in.nextInt();
        	for (int i = 1;i <= m;i++) {
        		int x,y;
        		x = in.nextInt();y = in.nextInt();
        		g[x].add(y);
        	}
        	for (int i = 1;i <= n;i++)
        		if (dfn[i]==0) dfs(i);
        	long ans = 0;
        	long way = 1;
        	for (int i = 1;i <= totn;i++) {
        		long mi = cost[(int)g1[i].get(0)];
        		long cnt = 1;
        		for (int j = 1;j < (int)g1[i].size();j++) {
        			int x = (int)g1[i].get(j);
        			x = cost[x];
        			if (x<mi) {
        				mi = x;
        				cnt = 1;
        			}else if (x==mi) cnt++;
        		}
        		ans = ans + mi;
        		way = (way*cnt)%((int)1e9 + 7);
        	}
        	out.println(ans+" "+way);
        }
    }

    static class InputReader{
        public BufferedReader br;
        public StringTokenizer tokenizer;

        public InputReader(InputStream ins) {
            br = new BufferedReader(new InputStreamReader(ins));
            tokenizer = null;
        }

        public String next(){
            while (tokenizer==null || !tokenizer.hasMoreTokens()) {
                try {
                tokenizer = new StringTokenizer(br.readLine());
                }catch(IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }
    }
}