sicily 1024 邻接矩阵与深度优先搜索解题

// Problem#: 1024
// Submission#: 2973318
// The source code is licensed under Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License
// URI: http://creativecommons.org/licenses/by-nc-sa/3.0/
// All Copyright reserved by Informatic Lab of Sun Yat-sen University
#include <iostream>
#include <stdio.h>
#include <map>
#include <vector>
#include <cstring>
using namespace std;

typedef struct node {
    int from;
    int edge;
    int to;
} Node; 

int longest;
map<int, vector<Node> > nodes;
bool visited[10001];

//深度优先搜索 
void DFS(int k, int distance) {
	bool deeper = false; //标记是否到达了叶子节点 
    for (int i = 0; i < nodes[k].size(); i++) {
        if (visited[nodes[k].at(i).to] == false) {     
            visited[nodes[k].at(i).to] = true;
            deeper = true;
            DFS(nodes[k].at(i).to, distance + nodes[k].at(i).edge);//此步很关键 
        }   
    }
	//如果到达了叶子节点则对该路径中的权值之和与最大距离比较 
    if (!deeper && distance > longest) {
    	longest = distance;
    }
}

int main() {
    int n, k;
    
    while (scanf("%d %d", &n, &k) != EOF) {//刚开始超时原来是忘了加 != EOF!!!!! 
    	
        memset(visited, false, sizeof(visited));
        
        //使用map容器建立邻接链表 
        for (int i= 0; i < n-1; i++) {  
            int from, edge, to;
            scanf("%d %d %d", &from, &to, &edge);
            Node temp;
            temp.from = from;
            temp.edge = edge;
            temp.to = to;
            nodes[from].push_back(temp);
             
            temp.from = to;
            temp.to = from;
            nodes[to].push_back(temp);
        }
        
       	longest = 0;
        int distance = 0;
        
        visited[k] = true;
        DFS(k, distance);
        cout << longest << endl;
        nodes.clear();
    }
    return 0;
}