sicily 1024 Magic Island

深搜中与记录长度有关的题目，都差不多是这样的！

还有邻接表的写法，不够熟！

#include <bits/stdc++.h>

using namespace std;

int ans;

bool vis[10005];

struct edge {
    int u;
    int v;
    int l;
};

vector <edge> graph[10005];

void dfs(int n, int x, int temp)
{
    if(ans < temp)
        ans=temp;
    vis[x]=1;
    for(int i=0; i<graph[x].size(); i++)
    {
        if(!vis[graph[x][i].v])
            dfs(n, graph[x][i].v, temp+graph[x][i].l);
    }
}


int main()
{
    int n,k;
    while(scanf("%d%d", &n, &k) != EOF)
    {
        ans=0;
        int temp=0;
        memset(graph, 0, sizeof(graph));
        memset(vis, 0, sizeof(vis));
        int u,v,l;
        for(int i=0; i<n-1; i++)
        {
            edge e;
            scanf("%d%d%d", &u, &v, &l);
            e.u = u;
            e.v = v;
            e.l = l;
            graph[u].push_back(e);    //注意是双向的啊!!! 
            e.u = v;
            e.v = u;
            e.l = l;
            graph[v].push_back(e);
        }
        
        dfs(n, k, temp);
        printf("%d
", ans);
    }
    return 0;
}