哦……LCT的一道更水的裸题，适合学习access，link，cut等基本操作（其实这三个不是在一个层面上的？不要在意这些细节……）
1 /************************************************************** 2 Problem: 2049 3 User: Tunix 4 Language: C++ 5 Result: Accepted 6 Time:1920 ms 7 Memory:1480 kb 8 ****************************************************************/ 9 10 //BZOJ 2049 11 #include<cstdio> 12 #include<cstring> 13 #include<cstdlib> 14 #include<iostream> 15 #include<algorithm> 16 #define rep(i,n) for(int i=0;i<n;++i) 17 #define F(i,j,n) for(int i=j;i<=n;++i) 18 #define D(i,j,n) for(int i=j;i>=n;--i) 19 using namespace std; 20 const int N=10086; 21 22 int c[N][2],fa[N],n,m,st[N<<1],top=0; 23 bool rev[N]; 24 25 void Push_down(int x){ 26 int l=c[x][0],r=c[x][1]; 27 if (rev[x]){ 28 rev[x]^=1; rev[l]^=1; rev[r]^=1; 29 swap(c[x][0],c[x][1]); 30 } 31 } 32 33 bool isroot(int x){ 34 return c[fa[x]][0]!=x && c[fa[x]][1]!=x; 35 } 36 37 void rotate(int x){ 38 int y=fa[x],z=fa[y],l=c[y][1]==x,r=l^1; 39 if (!isroot(y)) c[z][c[z][1]==y]=x; 40 fa[x]=z; fa[y]=x; fa[c[x][r]]=y; 41 c[y][l]=c[x][r]; c[x][r]=y; 42 } 43 44 void splay(int x){ 45 top=0; st[top++]=x; 46 for(int y=x;!isroot(y);y=fa[y]) 47 st[top++]=fa[y]; 48 while(top--) Push_down(st[top]); 49 50 while(!isroot(x)){ 51 int y=fa[x],z=fa[y]; 52 if (!isroot(y)){ 53 if(c[y][0]==x^c[z][0]==y) rotate(x); 54 else rotate(y); 55 } 56 rotate(x); 57 } 58 } 59 60 void access(int x){ 61 for(int t=0;x;t=x,x=fa[x]) 62 splay(x),c[x][1]=t; 63 } 64 65 void makeroot(int x){ 66 access(x); splay(x); rev[x]^=1; 67 } 68 69 int find(int x){ 70 access(x); splay(x); 71 while(c[x][0]) x=c[x][0]; 72 return x; 73 } 74 75 void cut(int x,int y){ 76 makeroot(x); 77 access(y); 78 splay(y); 79 if (c[y][0]==x) c[y][0]=fa[x]=0; 80 } 81 82 void link(int x,int y){ 83 makeroot(x); fa[x]=y; 84 } 85 //LCT end 86 int main(){ 87 // freopen("input.txt","r",stdin); 88 scanf("%d%d",&n,&m); 89 char cmd[10]; 90 int x,y; 91 F(i,1,m){ 92 scanf("%s%d%d",cmd,&x,&y); 93 if (cmd[0]=='C') link(x,y); 94 else if (cmd[0]=='D'){ 95 if (find(x)==find(y)) cut(x,y); 96 } 97 else if (cmd[0]=='Q'){ 98 if (find(x)==find(y)) printf("Yes\n"); 99 else printf("No\n"); 100 } 101 } 102 return 0; 103 }