poj2985（名次树（treap））找第k大 The k-th Largest Group

  有N只猫,开始每只猫都是一个小组,下面要执行M个操作,操作0 i j 是把i猫和j猫所属的小组合并,操作1 k 是问你当前第k大的小组大小是多少. 且k<=当前的最大组数.这里要注意,如果K>Treap中的节点总数,就默认输出1.(因为我们Treap只保存了合并之后的组大小)

#include<stdlib.h> struct Node {    Node *ch[2];    int r; //随机权值    int v; //值    int s; //附加域size    Node(int vv): v(vv) {        s = 1;        ch[0] = ch[1] = NULL;        r = rand();    }    int cmp(int x) const {        if(x == v) return -1;        return x < v ? 0 : 1;    }    void maintain() {        s = 1;        if(ch[0] != NULL) s += ch[0]->s;        if(ch[1] != NULL) s += ch[1]->s;    }}*root;void rotate(Node* &o, int d) { //旋转操作    Node* k = o->ch[d^1]; o->ch[d^1] = k->ch[d]; k->ch[d] = o;    o->maintain(); k->maintain(); o = k;}void insert(Node* &o, int x) { //插入操作    if(o == NULL) o = new Node(x);    else {        int d = x < o->v ? 0 : 1;  //注意相等时处理方式可以改变          insert(o->ch[d], x);        if(o->ch[d]->r > o->r) rotate(o, d^1);    }    o->maintain();}void remove(Node* &o, int x) { //删除操作    int d = o->cmp(x);    Node* u = o;    if(d == -1) {        if(o->ch[0] != NULL && o->ch[1] != NULL){            int d2 = o->ch[0]->r > o->ch[1]->r ? 1 : 0;            rotate(o, d2);            remove(o->ch[d2], x);        }        else {            if(o->ch[0] == NULL) o = o->ch[1]; else o = o->ch[0];            delete u;        }    }    else remove(o->ch[d], x);    if(o != NULL) o->maintain();}int kth(Node* o, int k) {//找第k大    if(o == NULL || k > o->s || k <= 0) return 1;    int s = o->ch[1] == NULL ? 0 : o->ch[1]->s;    if(k == s+1) return o->v;    else if(k <= s) return kth(o->ch[1], k);    else return kth(o->ch[0], k-s-1);}#include<cstdio>#include<cstring>#include<vector>using namespace std;const int mn=200005;int n,m;int f[mn],size[mn];int find_set(int x){int t=x;while(x!=f[x]) x=f[x];return f[t]=x;}int main(){root=NULL;scanf("%d%d",&n,&m);for(int i=1;i<=n;++i)f[i]=i,size[i]=1;while(m--){int cmp;scanf("%d",&cmp);if(cmp){int k;scanf("%d",&k);printf("%d\n",kth(root,k));}else{int u,v;scanf("%d%d",&u,&v);int fx=find_set(u),fy=find_set(v);if(fx!=fy){if(size[fx]!=1) remove(root,size[fx]);if(size[fy]!=1) remove(root,size[fy]);f[fy]=fx;size[fx]+=size[fy];insert(root,size[fx]);}}}return 0;}