单源最短路径

G.cpp

@@ -0,0 +1,63 @@
+# include <iostream>
+# include <cstdio>
+# include <cstring>
+# include <algorithm>
+# include <cmath>
+using namespace std;
+#define INF 0x3f3f3f3f
+#define Max 1001
+int cost[Max][Max];
+int d[Max];
+bool used[Max];
+void dijkstra(int n,int s)    
+{
+    memset(d,INF,sizeof(d));
+    memset(used,false,sizeof(used));
+    d[s]=0;
+    while(true)
+    {
+        int v=-1;
+        for(int u=0;u<n;u++)
+            if(!used[u]&&(v==-1||d[u]<d[v]))
+                v=u;
+        if(v==-1)
+            break;
+        used[v]=true;
+        for(int u=0;u<n;u++)
+        {
+            d[u]=min(d[u],d[v]+cost[u][v]);
+        }
+    }
+}
+ 
+int main()
+{
+    int T,m,n,k,i,j;
+    int from,to,Cost,f,t;
+    //freopen("in.txt","r",stdin);
+    cin>>T;
+    while(T--)
+    {
+        memset(cost,INF,sizeof(cost));
+        cin>>n>>m;
+        for(i=0;i<m;i++)
+        {
+            cin>>from>>to>>Cost;
+            cost[from][to]=cost[to][from]=Cost;
+        }
+        cin>>f>>t;
+        dijkstra(n,f);
+        int Time[Max],tim=0;
+        memset(Time,0,sizeof(Time));
+        for(i=0;i<n;i++)
+            Time[i]=d[i];
+        dijkstra(n,t);
+        for(i=0;i<n;i++)
+        {
+            Time[i]+=d[i];
+            tim=max(tim,Time[i]);
+        }
+        cout<<tim<<endl;
+ 
+    }
+}