hdu-2112 HDU Today---dijkstra+标号

题目链接：

http://acm.hdu.edu.cn/showproblem.php?pid=2112、

题目大意：

求起点到终点的最短路

解题思路：

对地名进行编号即可

然后直接dijkstra算法

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 typedef long long ll;
 4 const int maxn = 1000 + 10;
 5 const int INF = 0x3f3f3f3f;
 6 int Map[maxn][maxn];
 7 int v[maxn], d[maxn];
 8 int n, m;
 9 set<string>cnt;
10 map<string, int>G;
11 int GetID(string s)
12 {
13     if(cnt.count(s))return G[s];
14     cnt.insert(s);
15     return G[s] = cnt.size();
16 }
17 void dijkstra(int s, int t)
18 {
19     memset(v, 0, sizeof(v));
20     for(int i = 0; i <= n; i++)d[i] = (i == s ? 0 : INF);
21     for(int i = 0; i < n; i++)
22     {
23         int x = -1, m = INF;
24         for(int i = 1; i <= n; i++)if(!v[i] && d[i] <= m)m = d[x = i];
25         v[x] = 1;
26         for(int i = 1; i <= n; i++)
27         {
28             if(d[i] > d[x] + Map[x][i])
29             {
30                 d[i] = d[x] + Map[x][i];
31             }
32         }
33     }
34     if(d[t] == INF)d[t] = -1;
35     cout<<d[t]<<endl;
36 }
37 
38 int main()
39 {
40     while(scanf("%d", &n) != EOF && n != -1)
41     {
42         int u, v, w;
43         string s1,s2;
44         cnt.clear();
45         G.clear();
46         cin >> s1 >> s2;
47         int s = GetID(s1);
48         int t = GetID(s2);
49         memset(Map, INF, sizeof(Map));
50         while(n--)
51         {
52             cin >> s1 >> s2 >> w;
53             Map[GetID(s1)][GetID(s2)] = Map[GetID(s2)][GetID(s1)] = min(Map[GetID(s1)][GetID(s2)], w);
54         }
55         n = cnt.size();
56         dijkstra(s, t);
57     }
58 }

 

posted @ 2018-04-22 16:03  _努力努力再努力x  阅读(152)  评论(0)  编辑  收藏  举报