L2-001. 紧急救援（最短路的变形）*

L2-001. 紧急救援

 #include <cstdio>
 #include <algorithm>
 using namespace std;
 int const MAX = ;
 int const INF = 0x3fffffff;
 int mp[MAX][MAX], val[MAX], path[MAX], dis[MAX], re[MAX], totval[MAX], pathnum[MAX];
 bool vis[MAX];
 int n, m, s, d;

 void Dijkstra(int v0)
 {
     for(int i = ; i < n; i++)
         dis[i] = INF;
     vis[v0] = true;
     dis[v0] = ;
     totval[v0] = val[v0];
     pathnum[v0] = ;
     for(int i = ; i < n; i++)
     {
         if(mp[v0][i] != INF && i != v0)
         {
             dis[i] = mp[v0][i];
             path[i] = v0;
             totval[i] = val[v0] + val[i];
             pathnum[i] = ;
         }
     }
     for(int i = ; i < n - ; i++)
     {
         int mi = INF, mival = , u = v0;
         for(int j = ; j < n; j++)
         {
             if(!vis[j] && dis[j] < mi)
             {
                 mi = dis[j];
                 u = j;
             }
         }
         vis[u] = true;
         for(int j = ; j < n; j++)
         {
             if(!vis[j])
             {
                 if(dis[u] + mp[u][j] < dis[j])
                 {
                     pathnum[j] = pathnum[u];
                     dis[j] = dis[u] + mp[u][j];
                     totval[j] = totval[u] + val[j];
                     path[j] = u;
                 }
                 else if(dis[u] + mp[u][j] == dis[j])
                 {
                     pathnum[j] += pathnum[u];
                     if(totval[j] < totval[u] + val[j])
                     {
                         totval[j] = totval[u] + val[j];
                         path[j] = u;
                     }
                 }
             }
         }
     }
 }

 int main()
 {
     scanf("%d %d %d %d", &n, &m, &s, &d);
     for(int i = ; i < n; i++)
         scanf("%d", &val[i]);
     for(int i = ; i < n; i++)
         for(int j = ; j < n; j++)
             mp[i][j] = INF;
     int x, y, l;
     for(int i = ; i < m; i++)
     {
         scanf("%d %d %d", &x, &y, &l);
         mp[x][y] = min(mp[x][y], l);
         mp[y][x] = mp[x][y];
     }
     Dijkstra(s);
     int num = , cur = d;
     while(cur != s)
     {
         re[num ++] = cur;
         cur = path[cur];
     }
     re[num ++] = s;
     printf("%d %d\n", pathnum[d], totval[d]);
     for(int i = num - ; i > ; i--)
         printf("%d ", re[i]);
     printf("%d\n", re[]);
 }