luogu P4172 [WC2006]水管局长 LCT维护动态MST + 离线

#include<bits/stdc++.h>
#define maxn 1200000
#define N 120000 
using namespace std;                   
char *p1,*p2,buf[100000];
#define nc() (p1==p2&&(p2=(p1=buf)+fread(buf,1,100000,stdin),p1==p2)?EOF:*p1++)
int rd() {int x=0,f=1; char c=nc(); while(c<48) {if(c==‘-‘) f=-1; c=nc();} while(c>47) x=(((x<<2)+x)<<1)+(c^48),c=nc(); return x*f;}
void setIO(string s)
{
    string in=s+".in"; 
    string out=s+".out"; 
    freopen(in.c_str(),"r",stdin); 
    freopen(out.c_str(),"w",stdout); 
}
struct Union
{
    int p[maxn]; 
    inline void init() { for(int i=0;i<maxn;++i) p[i]=i; } 
    inline int find(int x) { return p[x]==x?x:p[x]=find(p[x]);  }
    inline int merge(int x,int y)
    {
        int a=find(x),b=find(y); 
        if(a==b) return 0; 
        p[a]=b; 
        return 1;   
    }
}con; 
struct LCT
{
    #define lson ch[x][0]
    #define rson ch[x][1] 
    #define isrt(x) (!(ch[f[x]][1]==x || ch[f[x]][0]==x)) 
    #define get(x) (ch[f[x]][1]==x)   
    int ch[maxn][2], maxv[maxn], rev[maxn], sumv[maxn], val[maxn], sta[maxn], idx[maxn], f[maxn];    
    inline void mark(int x) 
    {
        if(!x)return; 
        swap(lson,rson), rev[x]^=1; 
    }  
    inline void pushup(int x)
    {
        if(!x)return; 
        idx[x]=x, maxv[x]=val[x];           
        if(maxv[lson] > maxv[x]) idx[x] = idx[lson], maxv[x]=maxv[lson]; 
        if(maxv[rson] > maxv[x]) idx[x] = idx[rson], maxv[x]=maxv[rson]; 
        sumv[x]=sumv[lson]+sumv[rson]+val[x]; 
    }
    inline void pushdown(int x)
    {
        if(!x)return; 
        if(rev[x]) mark(lson), mark(rson), rev[x]^=1; 
    } 
    inline void rotate(int x)
    {
        int old=f[x],fold=f[old], which=get(x); 
        if(!isrt(old)) ch[fold][ch[fold][1]==old]=x; 
        ch[old][which]=ch[x][which^1], f[ch[old][which]]=old; 
        ch[x][which^1]=old, f[old]=x, f[x]=fold; 
        pushup(old), pushup(x); 
    }
    inline void splay(int x)
    {
        int u=x,v=0,fa; 
        for(sta[++v]=u;!isrt(u);u=f[u]) sta[++v]=f[u];         
        while(v) pushdown(sta[v--]);                      
        for(u=f[u];(fa=f[x])!=u;rotate(x)) 
            if(f[fa]!=u) 
                rotate(get(fa)==get(x)?fa:x); 
    }
    inline void Access(int x)
    {
        int t=0;
        while(x)
        {
            splay(x), rson=t, pushup(x), t=x,x=f[x]; 
        }
    }
    inline void MakeRoot(int x)
    {
        Access(x), splay(x), mark(x); 
    }
    inline void split(int x,int y)
    {
        MakeRoot(x), Access(y), splay(y); 
    }
    inline void cut(int x,int y)
    {
        MakeRoot(x), Access(y), splay(y); 
        ch[y][0]=f[x]=0; 
        pushup(y);   
    }   
    inline void link(int x,int y)
    {
        MakeRoot(x), f[x]=y;   
    }
}tr;    
int n,m,Q,eds; 
int from[maxn],to[maxn], cap[maxn], answer[maxn];  
map<int,int>ck[maxn]; 
struct OPT
{
    int o, x,y,eds, id, ans;  
}opt[maxn]; 
int main()
{
    int i,j;   
    setIO("input"); 
    con.init();   
    n=rd(),m=rd(),Q=rd(); 
    for(i=1;i<=m;++i)
    {
        ++eds;  
        from[eds]=rd(), to[eds]=rd(), cap[eds]=rd(); 
        ck[from[eds]][to[eds]]=ck[to[eds]][from[eds]]=eds;     
    } 
    for(i=1;i<=Q;++i)
    {
        opt[i].o=rd(); 
        if(opt[i].o==1) opt[i].x=rd(), opt[i].y=rd(); 
        if(opt[i].o==2) 
        {
            int a,b; 
            a=rd(),b=rd(); 
            opt[i].eds = ck[a][b]; 
            ck[a][b]=ck[b][a]=0; 
        }  
    }       
    for(i=1;i<=eds;++i)
    {
        if(ck[from[i]][to[i]]) 
        {   
            ++Q; 
            opt[Q].o=2; 
            opt[Q].eds=ck[from[i]][to[i]]; 
        }
    }                       
    for(i=Q;i>=1;--i)
    {

        if(opt[i].o==1)
        { 
            tr.split(opt[i].x,opt[i].y); 
            opt[i].ans=tr.maxv[opt[i].y];         
        }
        if(opt[i].o==2)
        {
            int cur=opt[i].eds,c,_new;   
            int x=from[cur], y=to[cur], cc=cap[cur],old; 
            if(con.merge(x, y)) 
            {
                _new=cur + n; 
                tr.val[_new]=tr.maxv[_new]=tr.sumv[_new]=cap[cur];   
                tr.link(_new, x), tr.link(_new, y);         
            }    
            else 
            {   
                tr.split(x,y);           
                c=tr.idx[y];      
                old=tr.val[c];   
                if(cc < old)  
                {
                    int a=from[c-n], b=to[c-n];         
                    tr.cut(a, c), tr.cut(b, c);   
                    _new=cur+n; 
                    tr.val[_new]=tr.maxv[_new]=tr.sumv[_new]=cap[cur];  
                    tr.link(_new, x), tr.link(_new, y);   
                }     
            }         
        }
    }
    for(i=1;i<=Q;++i)  if(opt[i].o==1) printf("%d\n",opt[i].ans); 
    return 0;    
}