hdu 2680 Choose the best route 解题报告

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=2680

题目意思：实质就是给定一个多源点到单一终点的最短路。

卑鄙题～～～有向图。初始化map时 千万不要写成 map[i][j] = map[j][i] = X。

 #include <iostream>
 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
 using namespace std;

 #define INF 0xfffffff
 const int maxn =  + ;
 int dist[maxn], map[maxn][maxn], vis[maxn];
 int n, m, s;

 void Init()
 {
     for (int i = ; i <= n; i++)
     {
         for (int j = ; j <= n; j++)
             map[i][j] = (i == j ?  : INF);
     }
     int p, q, t, w;
     for (int i = ; i < m; i++)
     {
         scanf("%d%d%d", &p, &q, &t);
         if (map[p][q] > t)
             map[p][q] = t;   // 写成map[p][q] = map[q][p] = t 会wa的！！！
     }
     scanf("%d", &w);
     for (int i = ; i < w; i++)
     {
         scanf("%d", &p);
         map[][p] = map[p][] = ;
     }
     for (int i = ; i <= n; i++)
         dist[i] = map[][i];
 }

 void Dijkstra()
 {
     int u, maxx;
     memset(vis, , sizeof(vis));
     for (int i = ; i <= n; i++)
     {
         maxx = INF;
         for (int j = ; j <= n; j++)
         {
             if (!vis[j] && dist[j] < maxx)
                 maxx = dist[u=j];
         }
         vis[u] = ;
         for (int j = ; j <= n; j++)
         {
             if (dist[j] > dist[u] + map[u][j])
                 dist[j] = dist[u] + map[u][j];
         }
     }
 }

 int main()
 {
     while (scanf("%d%d%d", &n, &m, &s) != EOF)
     {
         Init();
         Dijkstra();
         printf("%d\n", dist[s] == INF ? - : dist[s]);
     }
     return ;
 }