poj3256

bfs

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#include <iostream>

#include <cstdio>

#include <cstdlib>

#include <cstring>

using namespace std;



#define maxc 105

#define maxn 1005

#define maxm 10005



struct Edge

{

    int v, next;

} edge[maxm];



int cow, n, m;

int head[maxn];

int ncount;

bool vis[maxn];

int reach[maxn];

int q[maxn];

int pos[maxc];



void addedge(int a, int b)

{

    edge[ncount].v = b;

    edge[ncount].next = head[a];

    head[a] = ncount++;

}



void input()

{

    scanf("%d%d%d", &cow, &n, &m);

    for (int i = 0; i < cow; i++)

    {

        scanf("%d", &pos[i]);

        pos[i]--;

    }

    for (int i = 0; i < m; i++)

    {

        int a, b;

        scanf("%d%d", &a, &b);

        addedge(a - 1, b - 1);

    }

}



void bfs(int s)

{

    int front = 0, rear = 0;



    q[rear++] = s;

    vis[s] = true;

    while (front != rear)

    {

        int u = q[front++];

        reach[u]++;

        for (int i = head[u]; ~i; i = edge[i].next)

        {

            int v = edge[i].v;

            if (vis[v])

                continue;

            q[rear++] = v;

            vis[v] = true;

        }

    }

}



int work()

{

    memset(reach, 0, sizeof(reach));

    for (int i = 0; i < cow; i++)

    {

        memset(vis, 0, sizeof(vis));

        bfs(pos[i]);

    }

    int ret = 0;

    for (int i = 0; i < n; i++)

        if (reach[i] == cow)

            ret++;

    return ret;

}



int main()

{

    //freopen("t.txt", "r", stdin);

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

    ncount = 0;

    input();

    printf("%d\n", work());

    return 0;

}