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

 #include<bits/stdc++.h>
 using namespace std;
 typedef long long ll;
 const int maxn =  + ;
 const int INF = 0x3f3f3f3f;
 int Map[maxn][maxn];
 int v[maxn], d[maxn];
 int n, m;
 set<string>cnt;
 map<string, int>G;
 int GetID(string s)
 {
     if(cnt.count(s))return G[s];
     cnt.insert(s);
     return G[s] = cnt.size();
 }
 void dijkstra(int s, int t)
 {
     memset(v, , sizeof(v));
     for(int i = ; i <= n; i++)d[i] = (i == s ?  : INF);
     for(int i = ; i < n; i++)
     {
         int x = -, m = INF;
         for(int i = ; i <= n; i++)if(!v[i] && d[i] <= m)m = d[x = i];
         v[x] = ;
         for(int i = ; i <= n; i++)
         {
             if(d[i] > d[x] + Map[x][i])
             {
                 d[i] = d[x] + Map[x][i];
             }
         }
     }
     if(d[t] == INF)d[t] = -;
     cout<<d[t]<<endl;
 }

 int main()
 {
     while(scanf("%d", &n) != EOF && n != -)
     {
         int u, v, w;
         string s1,s2;
         cnt.clear();
         G.clear();
         cin >> s1 >> s2;
         int s = GetID(s1);
         int t = GetID(s2);
         memset(Map, INF, sizeof(Map));
         while(n--)
         {
             cin >> s1 >> s2 >> w;
             Map[GetID(s1)][GetID(s2)] = Map[GetID(s2)][GetID(s1)] = min(Map[GetID(s1)][GetID(s2)], w);
         }
         n = cnt.size();
         dijkstra(s, t);
     }
 }