LA5031 求多次删边的连通块的第K大数

题目链接：https://icpcarchive.ecs.baylor.edu/index.php?option=com_onlinejudge&Itemid=8&category=393&page=show_problem&problem=3032

白书原题源代码

#include<stdio.h>
#include<stdlib.h>
#include<algorithm>
#include<string.h>
using namespace std;
#define N 20005
struct Treap{
	Treap *ch[2];
	int r;			//数字越大，优先级越高
	int v;			//值
	int size;		//子树的节点数
	Treap(int v):v(v) { ch[0]=ch[1]=NULL; r=rand(); size=1;}
	bool operator < (const Treap& rhs) const{
		return r < rhs.r;
	}
	int cmp(int x) const{
		if(x == v)return -1;
		return x < v ? 0 : 1;
	}
	void maintain(){
		size = 1;
		if(ch[0] != NULL) size += ch[0]->size;
		if(ch[1] != NULL) size += ch[1]->size;
	}
};

void rotate(Treap* &o,int d){
	Treap* k = o->ch[d^1]; o->ch[d^1] = k->ch[d]; k->ch[d] = o;
	o->maintain(); k->maintain(); o = k;
}

void insert(Treap* &o,int x){
	if(o == NULL)  o = new Treap(x);
	else {
		int d = (x < o->v ? 0 : 1);
		insert(o->ch[d],x);
		if(o->ch[d] > o) rotate(o,d^1);
	}
	o->maintain();
}

void remove(Treap* &o,int x){
	int d = o->cmp(x);
	if(d == -1){
		Treap* u = o;
		if(o->ch[0] != NULL && o->ch[1] != NULL){
			int d2 = (o->ch[0] > o->ch[1] ? 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();
}
#define M 60005
struct Query{
	char Type;
	int x,p;
	Query(char a=0,int b=0,int c=0):Type(a),x(b),p(c){}
}query[500010];

int n,m,weight[N],from[M],to[M],removed[M];

int fa[N];
int findset(int x){return x==fa[x]? x : fa[x] = findset(fa[x]);}
Treap* root[N];

int kth(Treap* o,int k){
	if(o == NULL || k<=0 || k> o->size) return 0;
	int s = (o->ch[1] == NULL ? 0 : o->ch[1]->size);
	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);
}

void mergeto(Treap* &src,Treap* &dest){
	if(src->ch[0] != NULL) mergeto(src->ch[0],dest);
	if(src->ch[1] != NULL) mergeto(src->ch[1],dest);
	insert(dest,src->v);
	delete src;
	src = NULL;
}

void removetree(Treap* &x){
	if(x->ch[0] != NULL) removetree(x->ch[0]);
	if(x->ch[1] != NULL) removetree(x->ch[1]);
	delete x;
	x = NULL;
}

void add_edge(int x){
	int u = findset(from[x]),v = findset(to[x]);
	if(u != v){
		if(root[u]->size < root[v]->size) { fa[u] = v; mergeto(root[u],root[v]);}
		else { fa[v] = u; mergeto(root[v],root[u]);}
	}
}
int query_cnt;
long long query_tot;
void Q(int x,int k){
	query_cnt++;
	query_tot += kth(root[findset(x)],k);
}

void change_weight(int x,int v){
	int u = findset(x);
	remove(root[u],weight[x]);
	insert(root[u],v);
	weight[x] = v;
}

int main(){
	int Cas = 0;
	while(scanf("%d %d",&n,&m),n+m){
		for(int i = 1; i <= n; i++) scanf("%d",&weight[i]);
		for(int i = 1; i <= m; i++) scanf("%d%d",&from[i],&to[i]);
		memset(removed,sizeof(removed));

		int c = 0;
		while(1){
			char type; scanf(" %c",&type); if(type == 'E')break;
			int x,p = 0,v = 0;
			scanf("%d",&x);
			if(type == 'D') removed[x] = 1;
			if(type == 'Q') scanf("%d",&p);
			if(type == 'C') scanf("%d",&v);
			if(type == 'C') {
				scanf("%d",&v);
				p = weight[x];
				weight[x] = v;
			}
			query[c++] = Query(type,x,p);
		}
		for(int i = 1; i <= n; i++) {
			fa[i] = i; if(root[i] != NULL) removetree(root[i]);
			root[i] = new Treap(weight[i]);
		}
		for(int i =1; i <= m; i++) if(!removed[i]) add_edge(i);
		query_tot = query_cnt = 0;
		for(int i = c-1; i >= 0; i--) {
			if(query[i].Type == 'D') add_edge(query[i].x);
			if(query[i].Type == 'Q') Q(query[i].x,query[i].p);
			if(query[i].Type == 'C') change_weight(query[i].x,query[i].p);
		}
		printf("Case %d: %.6lfn",++Cas,query_tot / (double)query_cnt);
	}
	return 0;
}
/*
3 3
10
20 
30 
1 2 
2 3 
1 3 
D 3 
Q 1 2 
Q 2 1 
D 2 
Q 3 2 
C 1 50
Q 1 1
E

3 3 
10 
20 
20 
1 2 
2 3 
1 3 
Q 1 1 
Q 1 2 
Q 1 3 
E 
0 0

*/