洛谷 P3224 [HNOI2012]永无乡

传送门

同 AcWing 1063 永无乡

#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using p = pair<int, int>;
const int maxn(2e6 + 10);
int idx, root[maxn], pre[maxn];

struct node {
    int id;
    int val, siz;
    int fa, ch[2];
} tree[maxn];

template<typename T = int>
inline const T read()
{
    T x = 0, f = 1;
    char ch = getchar();
    while (ch < '0' || ch > '9') {
        if (ch == '-') f = -1;
        ch = getchar();
    }
    while (ch >= '0' && ch <= '9') {
        x = (x << 3) + (x << 1) + ch - '0';
        ch = getchar();
    }
    return x * f;
}

template<typename T>
inline void write(T x, bool ln)
{
    if (x < 0) {
        putchar('-');
        x = -x;
    }
    if (x > 9) write(x / 10, false);
    putchar(x % 10 + '0');
    if (ln) putchar(10);
}

inline int find(int cur)
{
    return pre[cur] == cur ? cur : pre[cur] = find(pre[cur]);
}

inline int new_node(int val, int id)
{
    ++idx;
    tree[idx].val = val;
    tree[idx].id = id;
    tree[idx].siz = 1;
    return idx;
}

inline int get_rel(int cur, int fa)
{
    return tree[fa].ch[1] == cur;
}

inline void push_up(int cur)
{
    tree[cur].siz = tree[tree[cur].ch[0]].siz + tree[tree[cur].ch[1]].siz + 1;
}

inline void connect(int cur, int fa, bool rel)
{
    tree[cur].fa = fa;
    tree[fa].ch[rel] = cur;
}

inline void rotate(int cur)
{
    int fa = tree[cur].fa;
    int gf = tree[fa].fa;
    bool rel = get_rel(cur, fa);
    connect(tree[cur].ch[rel ^ 1], fa, rel);
    connect(cur, gf, get_rel(fa, gf));
    connect(fa, cur, rel ^ 1);
    push_up(fa);
    push_up(cur);
}

inline void splaying(int cur, int top, int& rt)
{
    while (tree[cur].fa not_eq top) {
        int fa = tree[cur].fa;
        int gf = tree[fa].fa;
        if (gf not_eq top) {
            get_rel(cur, fa) ^ get_rel(fa, gf) ? rotate(cur) : rotate(fa);
        }
        rotate(cur);
    }
    if (not top) {
        rt = cur;
    }
}

inline void insert(int val, int id, int& rt)
{
    int cur = rt, fa = 0;
    while (cur) {
        fa = cur;
        cur = tree[cur].ch[val > tree[cur].val];
    }
    cur = new_node(val, id);
    connect(cur, fa, val > tree[fa].val);
    splaying(cur, 0, rt);
}

inline int get_id(int rank, int rt)
{
    int cur = rt;
    while (cur) {
        if (tree[tree[cur].ch[0]].siz >= rank) {
            cur = tree[cur].ch[0];
        } else if (tree[tree[cur].ch[0]].siz + 1 == rank) {
            break;
        } else {
            rank -= tree[tree[cur].ch[0]].siz + 1;
            cur = tree[cur].ch[1];
        }
    }
    return tree[cur].id;
}

inline void dfs(int u, int& v)
{
    if (not u) return;
    dfs(tree[u].ch[0], v);
    dfs(tree[u].ch[1], v);
    insert(tree[u].val, tree[u].id, v);
}

inline void merge(int u, int v)
{
    u = find(u);
    v = find(v);
    if (u not_eq v) {
        if (tree[root[u]].siz > tree[root[v]].siz) {
            swap(u, v);
        }
        dfs(root[u], root[v]);
        pre[u] = v;
    }
}

int main()
{
#ifdef ONLINE_JUDGE
#else
    freopen("input.txt", "r", stdin);
#endif
    int n = read(), m = read();
    for (int i = 1; i <= n; ++i) {
        pre[i] = root[i] = new_node(read(), i);
    }
    while (m--) {
        int u = read(), v = read();
        merge(u, v);
    }
    int q = read();
    while (q--) {
        char op[2];
        scanf("%s", op);
        int x = read(), k = read();
        if (*op == 'Q') {
            int rt = root[find(x)];
            if (tree[rt].siz < k) {
                write(-1, true);
            } else {
                write(get_id(k, rt), true);
            }
        } else {
            merge(x, k);
        }
    }
    return 0;
}