Create 5723.cpp

HDOJ/5723.cpp

@@ -0,0 +1,113 @@
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <algorithm>
+#include <vector>
+using namespace std;
+#define MAXN 100100
+#define MAXM 1000100
+#define MAXW 1000100
+using LL = long long;
+struct edge
+{
+    int u,v,w;
+};
+bool cmp(const edge& a,const edge& b)
+{
+    return a.w<b.w;
+}
+edge bus[MAXM];
+int father[MAXN];
+char vis[MAXN];
+
+/// Global For DFS
+int n,m;
+
+vector<pair<int,int>> vec[MAXN];
+
+int findfather(int x)
+{
+    return father[x]==x?x:father[x]=findfather(father[x]);
+}
+
+LL totalans;
+
+LL dfs(int index)
+{
+    vis[index]=1;
+    int sz=vec[index].size();
+    LL ksum=0;
+    LL nextans=0;
+    for(int i=0;i<sz;i++)
+    {
+        if(!vis[vec[index].at(i).first])
+        {
+            nextans=dfs(vec[index].at(i).first);
+            ksum+=nextans;
+            totalans+=(n-nextans)*nextans*vec[index].at(i).second;
+        }
+    }
+    return 1+ksum;
+}
+
+int main()
+{
+    int t;
+    scanf("%d",&t);
+    while(t--)
+    {
+        scanf("%d %d",&n,&m);
+        /// ...
+        if(n==0||m==0)
+        {
+            printf("0 0.00\n");
+            continue;
+        }
+        for(int i=0;i<=n;i++)
+        {
+            father[i]=i;
+        }
+        for(int i=0;i<MAXN;i++)
+        {
+            vec[i].clear();
+        }
+        memset(vis,0,sizeof(vis));
+
+        for(int i=0;i<m;i++)
+        {
+            scanf("%d %d %d",&bus[i].u,&bus[i].v,&bus[i].w);
+        }
+        sort(bus,bus+m,cmp);
+
+        LL sum=0;
+
+        int ss=0;
+        for(int cc=0;cc<m&&ss<n-1;cc++)
+        {
+            /// father[x]==x : x is standalone
+            int fu=findfather(bus[cc].u);
+            int fv=findfather(bus[cc].v);
+            if(fu!=fv)
+            {
+                father[fu]=fv;
+                ++ss;
+                sum+=bus[cc].w;
+                vec[bus[cc].u].push_back(make_pair(bus[cc].v,bus[cc].w));
+                vec[bus[cc].v].push_back(make_pair(bus[cc].u,bus[cc].w));
+            }
+        }
+
+        int b;
+        for(b=1;b<=n;b++)
+            /// FAQ: Why == 1 ? ANS: Because Nodes At the Edge of the graph has only 1 route.
+            if(vec[b].size()==1) break;
+
+        totalans=0;
+        dfs(b);
+
+        double tans=n*(n-1)/2.0;
+        /// Use Long Long?
+        printf("%I64d %.2lf\n",sum,(double)totalans/tans);
+    }
+    return 0;
+}