裸的LCT。
#include<iostream> #include<cstdio> #include<cstring> using namespace std; inline void Swap(int &a,int &b){a^=b^=a^=b;} void read(int &x){ 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 N 10005 int n,m,ch[N][2],fa[N],rev[N]; #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;} inline void Rev(int x){Swap(lc,rc),rev[x]^=1;} void down(int x){if(rev[x])Rev(lc),Rev(rc),rev[x]=0;} 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; } void splay(int x){ Pre(x); for(;nrt(x);turn(x)){ int y=fa[x],z=fa[y]; if(nrt(y)) turn(((ch[z][1]==y)^(ch[y][1]==x))?x:y); } } void access(int x){for(int y=0;x;y=x,x=fa[x])splay(x),rc=y;} 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; } int main(){ read(n);read(m); int q1,q2; char opt[12]; while(m--){ scanf("%s",opt); read(q1); read(q2); if(opt[0]=='Q') makert(q2),puts(findrt(q1)==q2?"Yes":"No"); else if(opt[0]=='C') link(q1,q2); else if(opt[0]=='D') cut(q1,q2); }return 0; }