hdu 2112 最短路+stl

很久以前做过的题，那个时候不知道为什么总是RE，现在没什么问题了，不过题目还是挺坑的，套了个实际的背景我还以为是有向边+起点终点不相同，实际上是无向边+起点终点可以相同...

  1 #include <iostream>
  2 #include <cstring>
  3 #include <string>
  4 #include <queue>
  5 #include <map>
  6 using namespace std;
  7 
  8 const int INF = 99999999;
  9 const int N = 201;
 10 const int M = 20000;
 11 int head[N];
 12 int dist[N];
 13 bool visit[N];
 14 int n, m, e;
 15 
 16 struct Edge
 17 {
 18     int v, next, w;
 19 } edge[M];
 20 
 21 void addEdge( int u, int v, int w )
 22 {
 23     edge[e].v = v;
 24     edge[e].w = w;
 25     edge[e].next = head[u];
 26     head[u] = e++;
 27 }
 28 
 29 void spfa( int s )
 30 {
 31     for ( int i = 1; i <= n; i++ )
 32     {
 33         dist[i] = INF;
 34         visit[i] = false;
 35     }
 36     dist[s] = 0;
 37     visit[s] = true;
 38     int q[N], top = 0;
 39     q[top] = s;
 40     top = ( top + 1 ) % n;
 41     for ( int i = 0; i != top; i = ( i + 1 ) % n )
 42     {
 43         int u = q[i];
 44         visit[u] = false;
 45         for ( int j = head[u]; j != -1; j = edge[j].next )
 46         {
 47             int v = edge[j].v, w = edge[j].w;
 48             if ( dist[v] > dist[u] + w )
 49             {
 50                 dist[v] = dist[u] + w;
 51                 if ( !visit[v] )
 52                 {
 53                     q[top] = v;
 54                     top = ( top + 1 ) % n;
 55                     visit[v] = true;
 56                 }
 57             }
 58         }
 59     }
 60 }
 61 
 62 map<string, int> mp;
 63 string from, to;
 64 
 65 int main ()
 66 {
 67     while ( cin >> m, m != -1 )
 68     {
 69         e = 0;
 70         n = 1;
 71         memset( head, -1, sizeof(head) );
 72         mp.clear();
 73         cin >> from >> to;
 74         int src = mp[from] = n++, des = src;
 75         if ( mp.count(to) == 0 )
 76         {
 77             des = mp[to] = n++;
 78         }
 79         while ( m-- )
 80         {
 81             int d;
 82             cin >> from >> to >> d;
 83             if ( mp.count(from) == 0 )
 84             {
 85                 mp[from] = n++;
 86             }
 87             if ( mp.count(to) == 0 )
 88             {
 89                 mp[to] = n++;
 90             }
 91             addEdge( mp[from], mp[to], d );
 92             addEdge( mp[to], mp[from], d );
 93         }
 94         n--;
 95         spfa(src);
 96         if ( dist[des] == INF ) dist[des] = -1;
 97         cout << dist[des] << endl;
 98     }
 99     return 0;
100 }

 

posted @ 2015-08-05 19:30  hxy_has_been_used  阅读(142)  评论(0)  编辑  收藏  举报