uva(11354) 最小瓶颈生成树+LCA

求出最小生成树后lca找最大权即可

#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;

struct my{
   int v;
   int next;
   int dist;
};

struct node{
   int x,y;
   int dist;
   bool operator <(const node& rhs) const {
      return dist<rhs.dist;
   }
};
const int maxn=100000+10;
my bian[maxn];
node edge[maxn];
int adj[maxn];
int anc[maxn][20];
int fa[maxn];
int L[maxn];
int fa1;
int m,n;
int maxcost[maxn][20];
int cost[maxn];

void init(){
  memset(adj,-1,sizeof(adj));
  memset(bian,-1,sizeof(bian));
  fa1=0;
  memset(fa,0,sizeof(fa));
  memset(anc,0,sizeof(anc));
  memset(maxcost,0,sizeof(maxcost));
  memset(cost,0,sizeof(cost));
}
void myinsert(int u,int v,int d){
     bian[++fa1].v=v;
     bian[fa1].next=adj[u];
     bian[fa1].dist=d;
     adj[u]=fa1;
}

void dfs(int u,int f,int dep){
     L[u]=dep;
     for (int i=adj[u];i!=-1;i=bian[i].next){
        int v=bian[i].v;
        if(v!=f){
        fa[v]=u;
        cost[v]=bian[i].dist;
        dfs(v,u,dep+1);
        }
     }
}
void RMQ(){
     for (int i=1;i<=n;i++){
        anc[i][0]=fa[i];
        maxcost[i][0]=cost[i];
        for (int j=1;(1<<j)<=n;j++) anc[i][j]=-1;
     }
     for (int j=1;(1<<j)<=n;j++){
            for (int i=1;i<=n;i++){
                    if(anc[i][j-1]!=-1){
                int a=anc[i][j-1];
                anc[i][j]=anc[a][j-1];
                maxcost[i][j]=max(maxcost[i][j-1],maxcost[a][j-1]);
            }
        }
     }
}

int getans(int p,int q){
    int log;
    if(L[p]<L[q]) swap(q,p);
    for (log=1;(1<<log)<=L[p];log++);
            log--;
    int ans=-10000;
    for (int i=log;i>=0;i--){
        if(L[p]-(1<<i)>=L[q]){
            ans=max(ans,maxcost[p][i]);
            p=anc[p][i];
        }
    }
    if(p==q) return ans;
    for (int i=log;i>=0;i--){
        if(anc[p][i]!=-1&&anc[p][i]!=anc[q][i]){
            ans=max(ans,maxcost[p][i]);
            ans=max(ans,maxcost[q][i]);
            p=anc[p][i];
            q=anc[q][i];
        }
    }
    ans=max(ans,cost[p]);
    ans=max(ans,cost[q]);
    return ans;
}

int getfather(int x){
    if(x==fa[x]) return x;
    else return fa[x]=getfather(fa[x]);
}
int main(){
    int kase=0;
    while(scanf("%d%d",&n,&m)!=EOF){
            init();
        int u,v,d;
        for (int i=1;i<=m;i++){
            scanf("%d%d%d",&u,&v,&d);
            edge[i].x=u;
            edge[i].y=v;
            edge[i].dist=d;
        }
        sort(edge+1,edge+m+1);
        for (int i=1;i<=n;i++) fa[i]=i;
        for (int i=1;i<=m;i++){
            int x=edge[i].x;
            int y=edge[i].y;
            int d=edge[i].dist;
            int u=getfather(x);
            int v=getfather(y);
            if(u!=v){
                fa[u]=v;
                myinsert(x,y,d);
                myinsert(y,x,d);
            }
        }
        dfs(1,-1,0);
        RMQ();
        int q,l,r;
        scanf("%d",&q);
        if(++kase!=1) printf(" ");
        while(q--){
            scanf("%d%d",&l,&r);
            printf("%d ",getans(l,r));
        }
    }
return 0;
}
/*1 2 3
2 1
3 4 1
4 3*/