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| #include <iostream>
#include <cstdio>
using namespace std;
const int N = 5e5 + 10;
int n, m, idx, p[N], rt[N];
struct Node
{
int p, v, id, sz, s[2];
void init(int a, int b, int c)
{
v = a;
id = b;
p = c;
sz = 1;
}
}tr[N];
int fa(int x)
{
return x == p[x] ? x : p[x] = fa(p[x]);
}
void pushup(int x)
{
tr[x].sz = tr[tr[x].s[0]].sz + tr[tr[x].s[1]].sz + 1;
}
void rotate(int x)
{
int y = tr[x].p, z = tr[y].p;
int k = tr[y].s[1] == x;
tr[z].s[tr[z].s[1] == y] = x;
tr[x].p = z;
tr[y].s[k] = tr[x].s[k ^ 1];
tr[tr[x].s[k ^ 1]].p = y;
tr[x].s[k ^ 1] = y;
tr[y].p = x;
pushup(y);
pushup(x);
}
void splay(int x, int k, int b)
{
while (tr[x].p != k)
{
int y = tr[x].p, z = tr[y].p;
if (z != k)
if ((tr[y].s[1] == x) ^ (tr[z].s[1] == y))
rotate(x);
else
rotate(x);
rotate(x);
}
if (!k)
rt[b] = x;
}
void insert(int v, int id, int b)
{
int u = rt[b], p = 0;
while (u)
{
p = u;
u = tr[u].s[v > tr[u].v];
}
u = ++idx;
if (p)
tr[p].s[v > tr[p].v] = u;
tr[u].init(v, id, p);
splay(u, 0, b);
}
int get_k(int k, int b)
{
int u = rt[b];
while (u)
{
if (tr[tr[u].s[0]].sz >= k)
u = tr[u].s[0];
else if (tr[tr[u].s[0]].sz + 1 == k)
return tr[u].id;
else
{
k -= tr[tr[u].s[0]].sz + 1;
u = tr[u].s[1];
}
}
return -1;
}
void dfs(int x, int b)
{
if (tr[x].s[0])
dfs(tr[x].s[0], b);
if (tr[x].s[1])
dfs(tr[x].s[1], b);
insert(tr[x].v, tr[x].id, b);
}
int main()
{
int n, m;
cin >> n >> m;
for (int i = 1, a; i <= n; i++)
{
p[i] = rt[i] = i;
cin >> a;
tr[i].init(a, i, 0);
}
idx = n;
while (m--)
{
int a, b;
cin >> a >> b;
a = fa(a);
b = fa(b);
if (a != b)
{
if (tr[rt[a]].sz > tr[rt[b]].sz)
swap(a, b);
dfs(rt[a], b);
p[a] = b;
}
}
cin >> m;
while (m--)
{
char op[2];
int a, b;
cin >> op >> a >> b;
if (op[0] == 'B')
{
a = fa(a);
b = fa(b);
if (a != b)
{
if (tr[rt[a]].sz > tr[rt[b]].sz)
swap(a, b);
dfs(rt[a], b);
p[a] = b;
}
}
else
{
a = fa(a);
if (tr[rt[a]].sz < b)
cout << -1 << endl;
else
cout << get_k(b, a) << endl;
}
}
return 0;
}
|