"Chu-Liu Algorithm" "Minimum tree diagram" hdu6141 I am your father!

Source: Internet
Author: User

Test instructions: give you a picture with the right direction, let you ask for the maximum tree shape chart. And on this premise ordered N-junction father's number is the smallest.

The game was a two-point, tle.

The weight of each side can actually be multiplied by 1000, for the parent edge of the n node, plus the weight of the (999-parent node number) size, so that the maximum tree is guaranteed, the number of the father of the N node is the smallest.

Online to find a Zhu-Liu algorithm of the board , the edge of the right to take negative can run the largest tree diagram.

#include <cstdio> #include <string> #include <cstring> #define MAXN 1005 #define MAXM 10005 using n  Amespace std;      struct node {int u, v;  int W;  }EDGE[MAXM];  int PRE[MAXN], ID[MAXN], VIS[MAXN], N, m;  int IN[MAXN];      typedef int type; #define INF 2000000000type directed_mst (int root, int V, int E) {type ret = 0;          while (true) {//1.?????          for (int i = 0; i < V; i++) in[i] = INF;              for (int i = 0; i < E; i++) {int u = edge[i].u;              int v = EDGE[I].V;          if (EDGE[I].W < in[v] && u! = V) {Pre[v] = u; in[v] = EDGE[I].W;}              } for (int i = 0; i < V; i++) {if (i = = root) continue;          if (in[i] = = INF) return-1;//???????????,???????          }//2.??          int cnt = 0;          memset (ID,-1, sizeof (ID));          memset (Vis,-1, sizeof (VIS));          In[root] = 0; for (int i = 0; i < V; i++)//?????              {ret + = In[i];              int v = i;              while (vis[v]! = i && id[v] = = 1 && v! = root)//?????????,?????????,???????                  {Vis[v] = i;              v = pre[v];              } if (v! = root && id[v] = =-1)//??                  {for (int u = pre[v]; u = v; u = pre[u]) id[u] = cnt;              ID[V] = cnt++; }} if (cnt = = 0) break;   //??                break for (int i = 0; i < V; i++) if (id[i] = = 1) id[i] = cnt++;          3.????              for (int i = 0; i < E; i++) {int u = edge[i].u;              int v = EDGE[I].V;              EDGE[I].U = Id[u];              EDGE[I].V = Id[v];          if (id[u]! = Id[v]) EDGE[I].W-= In[v];          } V = cnt;      root = Id[root];  } return ret; } int Zu,xs[10005],ys[10005],zs[10005];int Main () {//freopen ("1009.in", "R",stdin);//freopen ("1009.out", "w", stdout); scanf ("%d", &zu);        for (; zu;--zu) {scanf ("%d%d", &n, &m);              for (int i = 0; i < m; i++) {scanf ("%d%d%d", &edge[i].u, &AMP;EDGE[I].V, &AMP;EDGE[I].W);              edge[i].u--;              edge[i].v--;            edge[i].w*=1000;            if (edge[i].v==n-1) {edge[i].w+= (999-EDGE[I].U);            } EDGE[I].W=-EDGE[I].W;            xs[i]=edge[i].u;            YS[I]=EDGE[I].V;            ZS[I]=EDGE[I].W;             if (edge[i].u = = edge[i].v) {EDGE[I].W = INF;            Zs[i] = INF;          }} int ans = directed_mst (0, N, m);    printf ("%d%d\n", (-ans)/1000,1000-(-ans)%1000);  } return 0;   }

"Chu-Liu Algorithm" "Minimum tree diagram" hdu6141 I am your father!

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