//模拟赛里一道题要启发式合并，但我没想出来，我记得以前写过，结果发现原来是用线段树合并做的。。。
线段树合并：
#include<cstdio> #include<cstring> #include<cstdlib> #include<cmath> #include<algorithm> #include<iostream> #include<string> #include<ctime> #include<queue> #include<map> #include<set> #include<vector> typedef long long LL; using namespace std; const int N=100010; int n,m,q,fa[N],root[N],ls[N<<6],rs[N<<6],sum[N<<6],id[N],rk[N],cnt; char s[10]; int read() {int d=0,f=1; char c=getchar(); while (c<'0'||c>'9') {if (c=='-') f=-1; c=getchar();} while (c>='0'&&c<='9') d=(d<<3)+(d<<1)+c-48,c=getchar(); return d*f;} void judge(){freopen(".in","r",stdin); freopen(".out","w",stdout);} int ask(int x){return fa[x]==x?x:fa[x]=ask(fa[x]);} void insert(int &k,int l,int r,int x) { if (!k) k=++cnt; sum[k]++; if (l==r) return; int mid=(l+r)>>1; if (x<=mid) insert(ls[k],l,mid,x); else insert(rs[k],mid+1,r,x); } int query(int k,int l,int r,int x) { if (l==r) return l; int mid=(l+r)>>1; if (sum[ls[k]]>=x) return query(ls[k],l,mid,x); else return query(rs[k],mid+1,r,x-sum[ls[k]]); } int merge(int x,int y) { if (!x) return y; if (!y) return x; ls[x]=merge(ls[x],ls[y]); rs[x]=merge(rs[x],rs[y]); sum[x]=sum[ls[x]]+sum[rs[x]]; return x; } int main() { //judge(); n=read(); m=read(); for (int i=1;i<=n;i++) fa[i]=i; for (int i=1;i<=n;i++) rk[i]=read(); while (m--) { int x=read(),y=read(); fa[ask(x)]=ask(y); } for (int i=1;i<=n;i++) { insert(root[ask(i)],1,n,rk[i]); id[rk[i]]=i; } q=read(); while (q--) { scanf("%s",s); int x=read(),y=read(); if (s[0]=='Q') { int q=ask(x); if (sum[root[q]]<y) {puts("-1"); continue;} printf("%d ",id[query(root[q],1,n,y)]); } else { int q=ask(x),p=ask(y); if (q!=p) fa[q]=p,root[p]=merge(root[p],root[q]); } } return 0; }
splay启发式合并：
#include<cstdio> #include<cstring> #include<string> #include<cstdlib> #include<cmath> #include<iostream> #include<algorithm> #include<map> #include<set> #include<queue> #include<vector> #define mp make_pair #define pb push_back using namespace std; typedef long long LL; typedef pair<int,int> pa; const int N=100010; int n,m,fa[N],f[N],c[N][2],siz[N],a[N],tmp,b[N],cnt; //vector<int>e[N]; int Write[20],WRI; inline void judge(){freopen(".in","r",stdin);freopen(".out","w",stdout);} inline int read(){int d=0,f=1; char c=getchar(); while (c<'0'||c>'9'){if (c=='-') f=-1; c=getchar();} while (c>='0'&&c<='9') d=d*10+c-48,c=getchar(); return d*f;} inline void write(int x){if (!x){putchar('0'); return;}if (x<0) putchar('-'),x=-x;for (WRI=1;x;x/=10,WRI++) Write[WRI]=x%10;for (int i=WRI-1;i;i--) putchar((char)(Write[i]+48));} inline int ask(int x){return f[x]==x?x:f[x]=ask(f[x]);} inline void update(int x){siz[x]=siz[c[x][0]]+siz[c[x][1]]+1;} inline void rotate(int x,int &k) { int y=fa[x],z=fa[y],l=c[y][1]==x,r=l^1; if (y==k) k=x; else c[z][c[z][1]==y]=x; fa[c[x][r]]=y; fa[x]=z; fa[y]=x; c[y][l]=c[x][r]; c[x][r]=y; update(y); update(x); } inline void splay(int x,int &k) { while (x!=k) { int y=fa[x],z=fa[y]; if (y!=k) c[y][0]==x^c[z][0]==y?rotate(x,k):rotate(y,k); rotate(x,k); } } inline void insert(int x,int y) { c[y][0]=c[y][1]=0; siz[y]=1; for (;;) { if (a[y]<a[x]) { if (c[x][0]) x=c[x][0]; else { c[x][0]=y; fa[y]=x; splay(y,f[ask(x)]); return; } } else if (c[x][1]) x=c[x][1]; else { c[x][1]=y; fa[y]=x; splay(y,f[ask(x)]); return; } } } inline void dfs(int x) { if (c[x][0]) dfs(c[x][0]); if (c[x][1]) dfs(c[x][1]); b[++cnt]=x; } inline void Unite(int x,int y) { x=ask(x); y=ask(y); if (x==y) return; if (siz[x]<siz[y]) swap(x,y); cnt=0; dfs(y); for (int i=1;i<=cnt;i++) insert(ask(x),b[i]); } inline int query(int x,int k) { int res=-1; for (;x;) { if (siz[c[x][0]]+1==k) {res=x; return res;} if (siz[c[x][0]]>=k) x=c[x][0]; else k-=siz[c[x][0]]+1,x=c[x][1]; } return res; } int main() { //judge(); n=read(); m=read(); for (int i=1;i<=n;i++) a[i]=read(),f[i]=i,siz[i]=1; for (int i=1;i<=m;i++) Unite(read(),read()); m=read(); while (m--) { char s[2]; scanf("%s",s); int x=read(),y=read(); if (s[0]=='B') Unite(x,y); else printf("%d ",query(ask(x),y)); } return 0; }