朱刘算法模板

/*最小树形图图模版-朱刘算法模版说明：点标号必须0-(N-1) 必须去除到自身的点（到自身的边的边权赋无限大）NV表示总点数，NE表示总边数*/#define M 109#define type intconst 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.找最小入边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;//除了跟以外有点没有入边,则根无法到达它}//2.找环int cntnode = 0;memset(ID,-1,sizeof(ID));memset(vis,-1,sizeof(vis));In[root] = 0;for(int i=0;i<NV;i++) {//标记每个环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;//无环for(int i=0;i<NV;i++) if(ID[i] == -1) {ID[i] = cntnode ++;}//3.缩点,重新标记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;}