HDU 3726 Graph and Queries(treap)

//#include <bits/stdc++.h>
#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <algorithm>

using namespace std;

#define LL long long
#define pii pair<int, int>
#define MP make_pair
#define ls i << 1
#define rs ls | 1
#define md (ll + rr >> 1)
#define lson ll, md, ls
#define rson md + 1, rr, rs
#define inf 0x3f3f3f3f
#define N 3000010
#define M 100010

int ch
[2];
int rand_val
, key
, sz
, cnt
, tot;

int creat(int val){
++tot;
ch[tot][0] = ch[tot][1] = 0;
key[tot] = val;
rand_val[tot] = rand();
sz[tot] = cnt[tot] = 1;
return tot;
}
int cmp(int x, int val){
if(key[x] == val) return -1;
return key[x] < val ? 1 : 0;
}
void push_up(int x){
sz[x] = cnt[x] + sz[ch[x][0]] + sz[ch[x][1]];
}
void rot(int &x, int d){
int k = ch[x][d^1];
ch[x][d^1] = ch[k][d];
ch[k][d] = x;
push_up(x);
push_up(k);
x = k;
}
void insert(int &x, int val){
if(x == 0){
x = creat(val);
return ;
}
int d = cmp(x, val);
if(d == -1){
sz[x]++, cnt[x]++;
return ;
}
insert(ch[x][d], val);
if(rand_val[ch[x][d]] > rand_val[x]) rot(x, d ^ 1);
push_up(x);
}
void dele(int &x, int val){
if(x == 0) return ;
int d = cmp(x, val);
if(d == -1){
if(cnt[x] > 1){
cnt[x]--, sz[x]--;
return ;
}
if(!ch[x][0]) x = ch[x][1];
else if(!ch[x][1]) x = ch[x][0];
else{
int d2 = rand_val[ch[x][0]] > rand_val[ch[x][1]] ? 1 : 0;
rot(x, d2);
dele(ch[x][d2], val);
}
}
else dele(ch[x][d], val);
if(x) push_up(x);
}
int kth(int x, int k){
if(!x) return -inf;
int tmp = sz[ch[x][1]];
if(k <= tmp) return kth(ch[x][1], k);
k -= tmp;
if(k <= cnt[x]) return key[x];
return kth(ch[x][0], k - cnt[x]);
}

struct edge{
int u, v;
void input(){
scanf("%d%d", &u, &v);
}
};
struct oper{
char s[3];
int u, k;
oper(){
u = -1, k = -1;
}
};

edge E[M];
oper Q[M*5];
int val[M], fa[M], rt[M];
bool del[M];
void unin(int a1, int a2){
if(sz[rt[a1]] < sz[rt[a2]]) swap(a1, a2);
while(1){
int tmp = kth(rt[a2], 1);
if(tmp == -inf) break;
insert(rt[a1], tmp);
dele(rt[a2], tmp);
}
fa[a2] = a1;
rt[a2] = 0;
}

int find(int x){
if(fa[x] != x) fa[x] = find(fa[x]);
return fa[x];
}
int main(){
int n, m, cas = 0;
while(scanf("%d%d", &n, &m) != EOF && (n || m)){
memset(del, 0, sizeof del);
for(int i = 1; i <= n; ++i)
scanf("%d", &val[i]);
for(int i = 1; i <= m; ++i)
E[i].input();
int q = 0;
while(1){
scanf("%s", Q[q].s);
if(Q[q].s[0] == 'E') break;
if(Q[q].s[0] == 'D'){
scanf("%d", &Q[q].u);
del[Q[q].u] = 1;
}
else{
scanf("%d%d", &Q[q].u, &Q[q].k);
if(Q[q].s[0] == 'C'){
int tmp = val[Q[q].u];
val[Q[q].u] = Q[q].k, Q[q].k = tmp;
}
}
q++;
}
tot = 0;
memset(rt, 0, sizeof rt);
for(int i = 1; i <= n; ++i) fa[i] = i, insert(rt[i], val[i]);
for(int i = 1; i <= m; ++i){
if(!del[i]){
int u = E[i].u, v = E[i].v;
if(find(u) == find(v)) continue;
unin(find(u), find(v));
}
}
LL ans = 0;
int tim = 0;
for(int i = q - 1; i >= 0; --i){
if(Q[i].s[0] == 'Q'){
int v = find(Q[i].u);
int ret = kth(rt[v], Q[i].k);
if(ret != -inf)
ans += ret;
tim++;
}
else if(Q[i].s[0] == 'C'){
int v = find(Q[i].u);
dele(rt[v], val[Q[i].u]);
insert(rt[v], Q[i].k);
val[Q[i].u] = Q[i].k;
}
else{
int k = Q[i].u;
int u = E[k].u, v = E[k].v;
if(find(u) == find(v)) continue;
unin(find(u), find(v));
}
}
printf("Case %d: %.6f\n", ++cas, ans * 1.0 / tim);
}

return 0;
}