題目大意：維護一個森林，支持邊的斷，連，以及查詢連通性

LCT裸題 洛谷P2147傳送門

1A了，給自己鼓鼓掌

 1 #include <cstdio>
 2 #include <algorithm>
 3 #include <cstring>
 4 #define il inline
 5 #define inf 500000
 6 #define N 10100
 7 using namespace std;
 8 
 9 int n,m,tp;
10 int stk[N];
11 struct LinkCutTree{
12     int fa[N],ch[N][2
 
],rv[N];
13     il int idf(int x){return ch[fa[x]][0]==x?0:1;}
14     il void con(int x,int ff,int p){fa[x]=ff,ch[ff][p]=x;}
15     il int isroot(int x){return (ch[fa[x]][0]!=x&&ch[fa[x]][1]!=x)?1:0;}
16     il void rev(int x){swap(ch[x][0],ch[x][1]),rv[x]^=1;}
17     il void pushdown(int x)
18     {
 
19         if(!rv[x]) return;
20         if(ch[x][0]) rev(ch[x][0]);
21         if(ch[x][1]) rev(ch[x][1]);
22         rv[x]=0;
23     }
24     il void rot(int x)
25     {
26         int y=fa[x];int ff=fa[y];int px=idf(x);int py=idf(y);
27         if(!isroot(y)) ch[ff][py]=x;
28         fa[x]=ff;con(ch[x][px^1
 
],y,px),con(y,x,px^1);
29         //pushup(y),pushup(x);
30     }
31     void splay(int x)
32     {
33         int y=x;stk[++tp]=x;
34         while(!isroot(y)){stk[++tp]=fa[y],y=fa[y];}
35         while(tp){pushdown(stk[tp--]);}
36         while(!isroot(x))
37         {
38             y=fa[x];
39             if(isroot(y)) rot(x);
40             else if(idf(y)==idf(x)) rot(y),rot(x);
41             else rot(x),rot(x);
42         }
43     }
44     void access(int x){for(int y=0;x;y=x,x=fa[x])splay(x),ch[x][1]=y;/*pushup(x)*/}
45     il void mkroot(int x){access(x),splay(x),rev(x);}
46     il void split(int x,int y){mkroot(x),access(y),splay(y);}
47     int findrt(int x){access(x),splay(x);while(ch[x][0])pushdown(x),x=ch[x][0];return x;}
48     il void link(int x,int y){mkroot(x);if(findrt(y)!=x)fa[x]=y;}
49     il void cut(int x,int y){mkroot(x);if(findrt(y)==x&&fa[x]==y&&!ch[x][1])fa[x]=ch[y][0]=0;/*pushup(y)*/}
50 }lct;
51 int gint()
52 {
53     int rett=0,fh=1;char c=getchar();
54     while(c<‘0‘||c>‘9‘){if(c==‘-‘)fh=-1;c=getchar();}
55     while(c>=‘0‘&&c<=‘9‘){rett=(rett<<3)+(rett<<1)+c-‘0‘;c=getchar();}
56     return rett*fh;
57 }
58 
59 int main()
60 {
61     n=gint(),m=gint();
62     int fl,x,y;char str[20];
63     for(int i=1;i<=m;i++)
64     {
65         scanf("%s",str);
66         x=gint(),y=gint();
67         if(str[0]==‘C‘){lct.link(x,y);}
68         if(str[0]==‘D‘){lct.cut(x,y);}
69         if(str[0]==‘Q‘){
70             if(lct.findrt(x)==lct.findrt(y))
71                 printf("Yes\n");
72             else printf("No\n");}
73     }
74     return 0;
75 }

bzoj 2049 [SDOI2008]洞穴勘測 (LCT)