[HNOI2012] 永无乡 题解

 1 #include<cstdio>
 2 const int M=100005,N=5500000;
 3 int sz,a[M],p[M],g[M],id[M],lc[N],rc[N],sum[N];
 4 char c[5];
 5 
 6 int read()
 7 {
 8     int x=0; char ch=getchar();
 9     while (ch<48 || ch>57) ch=getchar();
10     while (ch>47 && ch<58) x=(x<<1)+(x<<3)+ch-48,ch=getchar();
11     return x;
12 }
13 
14 int find(int x) { for (;x^p[x];x=p[x]=p[p[x]]); return x; }
15 
16 void add(int l,int r,int &k,int x)
17 {
18     if (!k) k=++sz; ++sum[k];
19     if (l==r) return;
20     int mid=l+r>>1;
21     if (x>mid) add(mid+1,r,rc[k],x);
22     else add(l,mid,lc[k],x);
23 }
24 
25 int merge(int x,int y)
26 {
27     if (!x || !y) return x|y;
28     lc[x]=merge(lc[x],lc[y]),rc[x]=merge(rc[x],rc[y]);
29     sum[x]=sum[lc[x]]+sum[rc[x]];
30     return x;
31 }
32 
33 int ask(int l,int r,int cur,int k)
34 {
35     if (l==r) return l;
36     int mid=l+r>>1;
37     if (sum[lc[cur]]<k) return ask(mid+1,r,rc[cur],k-sum[lc[cur]]);
38     else return ask(l,mid,lc[cur],k);
39 }
40 
41 int main()
42 {
43     int n=read(),m=read(),i,x,y;
44     for (i=1;i<=n;++i) id[a[i]=read()]=i,p[i]=i;
45     for (i=1;i<=m;++i) p[find(read())]=find(read());
46     for (i=1;i<=n;++i) add(1,n,g[find(i)],a[i]);
47     for (m=read();m--;)
48         if (scanf("%s",c),x=read(),y=read(),c[0]==‘Q‘)
49             if (sum[g[x=find(x)]]<y) puts("-1");
50             else printf("%d\n",id[ask(1,n,g[x],y)]);
51         else
52             if ((x=find(x))^(y=find(y)))
53                 if (sum[y]<sum[x]) p[y]=x,g[x]=merge(g[x],g[y]);
54                 else p[x]=y,g[y]=merge(g[y],g[x]);
55     return 0;
56 }