Copy the code code as follows:
/*
Minimum tree diagram template-Zhu Liu algorithm
Template description: Point label must be 0-(N-1)
Points to itself must be removed (the edge weight of the edge to itself is infinite)
*/
#define M 109
#define type int
const type inf=(1)<<30;
struct Node{
int u , v;
type cost;
}E[M*M+5];
int pre[M],ID[M],vis[M];
type In[M];
int n,m;
type Directed_MST(int root,int NV,int NE) {
type ret = 0;
while(true) {
//1. Find the smallest entry edge
for(int i=0;i<NV;i++) In[i] = inf;
for(int i=0;i<NE;i++){
int u = E[i].u;
int v = E[i].v;
if(E[i].cost < In[v] && u != v) {
pre[v] = u;
In[v] = E[i].cost;
}
}
for(int i=0;i<NV;i++) {
if(i == root) continue;
if(In[i] == inf)return -1;//There is no incoming edge except the following point, then the root cannot reach it
}
//2. Find the ring
int cntnode = 0;
memset(ID,-1,sizeof(ID));
memset(vis,-1,sizeof(vis));
In[root] = 0;
for(int i=0;i<NV;i++) {//Mark each ring
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] = cntnode;
}
ID[v] = cntnode++;
}
}
if(cntnode == 0)break;//No loop
for(int i=0;i<NV;i++) if(ID[i] == -1) {
ID[i] = cntnode++;
}
//3. Shrink points and re-mark
for(int i=0;i<NE;i++) {
int v = E[i].v;
E[i].u = ID[E[i].u];
E[i].v = ID[E[i].v];
if(E[i].u != E[i].v) {
E[i].cost -= In[v];
}
}
NV = cntnode;
root = ID[root];
}
return ret;
}