搜狗笔试

第三题

package sougo;

import org.junit.Test;

import java.util.*;

public class Main01 {
    class Interval {
        int start;
        int end;

        Interval(int start, int end) {
            this.start = start;
            this.end = end;
        }
    }
    public boolean[] bfs(List<Integer>[] g, int n, int start) {
        boolean[] res = new boolean[n];
        boolean[] used = new boolean[n];
        Queue<Integer> q =  new LinkedList<>();
        q.offer(start);used[start] = true;
        while(!q.isEmpty()) {
            int cur = q.poll();
            res[cur] = true;
            for(int i=0; i < g[cur].size(); i++) {
                int item = g[cur].get(i);
                if(used[item] == false) {
                    q.offer(item);
                    used[item] = true;
                }

            }
        }
        return res;
    }
    public Interval trim (int N, int M, Interval[] conn) {
        // write code here
        int n = N+2;
        List<Integer>[] g = new ArrayList[n];
        for(int i=0; i < n; i++) g[i] = new ArrayList();
        for(int i=0;  i < M; i++) {
            //System.out.println(i);
            int a = conn[i].start, b = conn[i].end;
            if(b == -1) {
                b = N+1;
            }
            g[a].add(b);
            //g[b].add(a);
        }
        boolean[] res1 = bfs(g, n, 0);

        g = new ArrayList[n];
        for(int i=0; i < n; i++) g[i] = new ArrayList();
        for(int i=0;  i < M; i++) {
            //System.out.println(i);
            int a = conn[i].start, b = conn[i].end;
            if(b == -1) {
                b = N+1;
            }
            //g[a].add(b);
            g[b].add(a);
        }

        boolean[] res2 = bfs(g, n, N+1);

        int res = 0;int sum = 0, mod = 100000007;
        for(int i=1; i <= N; i++) {
            if(res1[i] && res2[i]) {
                res++;
                sum = (sum + i) % mod;
            }
        }
        return new Interval(res, sum);
    }
//3,4,[[0,1],[0,2],[2,-1],[2,1]]
    @Test
    public void test() {

        int N = 3;
        int M = 4;
        Interval[] conn = new Interval[M];
        conn[0] = new Interval(0,1);
        conn[1] = new Interval(0,2);
        conn[2] = new Interval(2,-1);
        conn[3] = new Interval(2,1);
        Interval trim = trim(N, M, conn);
        System.out.println(trim.start +" " + trim.end);

    }
}