Sicily-1024

一． 题意：

有n个节点，n-1条边，并且任意两个节点都连通。模拟一下，实际上是一棵树的便利，求从特定根节点出发最长路径的值。这里用了广搜。

二． 每个节点只有两条邻接边，每个节点用一个vector来存储这些边。还有isVisited数组保证一条路径中一个节点只能经过一次。

三．

 1 //
 2 //  main.cpp
 3 //  sicily-1024
 4 //
 5 //  Created by ashley on 14-10-13.
 6 //  Copyright (c) 2014年 ashley. All rights reserved.
 7 //
 8 
 9 #include <iostream>
10 #include <vector>
11 using namespace std;
12 typedef struct
13 {
14     int left;
15     int right;
16     int weight;
17 }edge;
18 vector<edge> route;
19 vector<edge> adj[10001];
20 bool isVisited[10001];
21 void breadthSearch(int source, int &length, int pathLength)
22 {
23     isVisited[source] = true;
24     for (int i = 0; i < (int)adj[source].size(); i++) {
25         if (isVisited[adj[source][i].right] == false || isVisited[adj[source][i].left] == false) {
26             if (pathLength + adj[source][i].weight > length) {
27                 length = pathLength + adj[source][i].weight;
28             }
29             if (isVisited[adj[source][i].right] == false) {
30                 breadthSearch(adj[source][i].right, length, pathLength + adj[source][i].weight);
31             }
32             if (isVisited[adj[source][i].left] == false) {
33                 breadthSearch(adj[source][i].left, length, pathLength + adj[source][i].weight);
34             }
35         }
36     }
37 }
38 int main(int argc, const char * argv[])
39 {
40     int nodeNum, capital;
41     while (cin >> nodeNum >> capital) {
42         for (int i = 0; i < 10001; i++) {
43             adj[i].clear();
44             isVisited[i] = false;
45         }
46         //memset(adj, 0, sizeof(adj));
47         //memset(isVisited, 0, sizeof(isVisited));
48         int l, r, w;
49         for (int i = 0; i < nodeNum - 1; i++) {
50             cin >> l >> r >> w;
51             adj[l].push_back(edge{l, r, w});
52             adj[r].push_back(edge{l, r, w});
53         }
54         int longest = 0;
55         breadthSearch(capital, longest, 0);
56         cout << longest << endl;
57     }
58     return 0;
59 }

 

源代码

posted on 2014-12-08 19:39  ashleyblog  阅读(159)  评论(0)  编辑  收藏  举报