P4172 [WC2006]水管局长（LCT）

P4172 [WC2006]水管局长

LCT维护最小生成树，边权化点权。类似 P2387 [NOI2014]魔法森林（LCT）

离线存储询问，倒序处理，删边改加边。

#include<iostream>
#include<cstdio>
#include<cstring>
#define rint register int
using namespace std;
inline void Swap(int &a,int &b){a^=b^=a^=b;}
void read(int &x){
    static char c=getchar();x=0;
    while(c<'0'||c>'9') c=getchar();
    while('0'<=c&&c<='9') x=x*10+(c^48),c=getchar();
}
#define M 200005
int n,m,Q,ch[M][2],fa[M],val[M],s[M],rev[M]; bool del[M];
int mp[1005][1005],p1[M],p2[M],p3[M],q1[M],q2[M],q3[M],ans[M];
#define lc ch[x][0]
#define rc ch[x][1]
inline bool nrt(int x){return ch[fa[x]][0]==x||ch[fa[x]][1]==x;}
void up(int x){//维护最大边化为的点的编号
    s[x]=x;
    if(val[s[lc]]>val[s[x]]) s[x]=s[lc];
    if(val[s[rc]]>val[s[x]]) s[x]=s[rc];
}
inline void Rev(int x){Swap(lc,rc),rev[x]^=1;}
void down(int x){if(rev[x])Rev(lc),Rev(rc),rev[x]^=1;}
void Pre(int x){if(nrt(x))Pre(fa[x]); down(x);}
void turn(int x){
    int y=fa[x],z=fa[y],l=(ch[y][1]==x),r=l^1;
    if(nrt(y)) ch[z][ch[z][1]==y]=x;
    fa[ch[x][r]]=y; fa[y]=x; fa[x]=z;
    ch[y][l]=ch[x][r]; ch[x][r]=y;
    up(y); up(x);
}
void splay(int x){
    Pre(x);
    for(;nrt(x);turn(x)){
        int y=fa[x],z=fa[y];
        if(nrt(y)) turn((ch[y][1]==z)^(ch[z][1]==y)?x:y);
    }
}
void access(int x){for(int y=0;x;y=x,x=fa[x])splay(x),rc=y,up(x);}
inline void makert(int x){access(x),splay(x),Rev(x);}
int findrt(int x){
    access(x);splay(x);down(x);
    while(lc) x=lc,down(x);
    splay(x); return x;
}
void link(int x,int y){makert(x); if(findrt(y)!=x) fa[x]=y;}
void cut(int x,int y){
    makert(x);
    if(findrt(y)==x&&fa[y]==x&&!ch[y][0]) fa[y]=rc=0,up(x);
}
inline void split(int x,int y){makert(x),access(y),splay(y);}
void ins(int i){
    bool is=1;
    if(findrt(p1[i])==findrt(p2[i])){//已经连在一起
        split(p1[i],p2[i]); int w=s[p2[i]];
        if(val[w]>p3[i])
            cut(p1[w-n],w),cut(w,p2[w-n]);//删除最大边
        else is=0;
    }if(is) link(p1[i],n+i),link(n+i,p2[i]);
}
int main(){
    read(n);read(m);read(Q);
    for(rint i=1;i<=m;++i){
        read(p1[i]),read(p2[i]),read(p3[i]);
        mp[p1[i]][p2[i]]=mp[p2[i]][p1[i]]=i;
        val[n+i]=p3[i];
    }
    for(rint i=1;i<=Q;++i){
        read(q1[i]),read(q2[i]),read(q3[i]);
        if(q1[i]==2) del[mp[q2[i]][q3[i]]]=1;
    }
    for(rint i=1;i<=m;++i) if(!del[i]) ins(i);
    for(rint i=Q;i>=1;--i){//倒序处理询问
        if(q1[i]==2) ins(mp[q2[i]][q3[i]]);
        else split(q2[i],q3[i]),ans[i]=val[s[q3[i]]];
    }
    for(rint i=1;i<=Q;++i) if(q1[i]==1) printf("%d\n",ans[i]);
    return 0;
}