LightOj 1111 - Best Picnic Ever

/***   Author: johnsondu*   time: 2013-4-11*   problem: LightOj 1111 - Best Picnic Ever*   url: http://lightoj.com/volume_showproblem.php?problem=1111*   stratege: DFS, count the person who can run into city i, and*               let the corresponding dp[i] plus 1, finally, when*               city i meet the problem need, dp[i] must be the person*               number.*/#include <iostream>#include <algorithm>#include <string>#include <vector>#include <cstring>#include <cstdio>#define M 1005#define inf 0xfffffff#define min(x, y) (x < y ? x : y)using namespace std ;int mat[M][M], person[M] ;int n, m, t, ans ;bool mark[M] ;bool flag, flag1 ;int dp[M] ;void init (){    int a, b, i ;    ans = 0;    for (int i = 0; i < t; i ++)        scanf ("%d", &person[i]) ;    memset (mat, 0, sizeof (mat)) ;    for (i = 0; i < m; i ++)    {        scanf ("%d%d", &a, &b) ;        mat[a][b] = 1 ;    }}void DFS (int x, int y){    for (int i = 1; i <= n; i ++)    {        if (x == i)            continue ;        if (!mark[i] && mat[x][i])        {            mark[i] = true ;            dp[i] ++ ;            DFS (i, y) ;        }    }}void solve (){    int i, j ;    memset (dp, 0, sizeof (dp)) ;    for (j = 0; j < t; j ++)    {        memset (mark, false, sizeof (mark)) ;        mark[person[j]] = true ;        dp[person[j]] ++ ;        DFS (person[j], person[j]) ;    }    for (i = 1; i <= n; i ++)        if (dp[i] == t)            ans ++ ;}int main (){    int tcase, cas = 1 ;    //freopen ("data.txt", "r", stdin) ;    scanf ("%d", &tcase) ;    while (tcase --)    {        scanf ("%d%d%d", &t, &n, &m) ;        init () ;        solve () ;        printf ("Case %d: %d\n", cas ++, ans) ;    }    return 0 ;}