Codeforces 120F Spiders

看了chenxing老湿的代码，我真心为自己智商捉鸡啊。。一遍dfs搞定啊。。

#include <cstdio>
#include <cstring>
#define maxn 110
int first[maxn],v[maxn*2],next[maxn*2];
int len,e;
inline int max(int a,int b){
    return a > b ? a : b;
}

void init(){
    e = 0;
    memset(first,-1,sizeof(first));
}

void add_edge(int a,int b){
    v[e] = b;
    next[e] = first[a];
    first[a] = e++;
}

int dfs(int u,int fa){
    int ret = 0,maxdep;
    for(int i = first[u];i != -1;i = next[i]){
        if(v[i] == fa)  continue;
        maxdep = dfs(v[i],u);
        len = max(len,ret + maxdep + 1);
        ret = max(ret,maxdep + 1);
    }
    return ret;
}

int main(){
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    int n,m;
    while(scanf("%d",&n) != EOF){
        int ans = 0;
        while(n--){
            scanf("%d",&m);
            init();
            len = 0;
            for(int i = 0;i < m-1;i++){
                int a,b;
                scanf("%d%d",&a,&b);
                add_edge(a,b);
                add_edge(b,a);
            }
            dfs(1,-1);
            ans += len;
        }
        printf("%d
",ans);
    }
}