BZOJ 2733 [HNOI2012]永无乡 Treap + 并查集

题目链接

题意

给定一个图，每个点上有权值。两种操作，连结两个点；问与某个点连通的所有点中权值为第 k 小的点的编号。

思路

HDU 3726 Graph and Queries 离线处理 treap + 并查集 的简易版，直接正着做，也没有修改操作

Code

#include <bits/stdc++.h>#define maxn 100010int fa[maxn], sz[maxn], val[maxn];using namespace std;map<int, int> mp;struct node {    int key, val, sz;    node* ch[2];    node() { sz = 0, key = INT_MAX; }    node(int x);    void update() { sz = ch[0]->sz + ch[1]->sz + 1; }}*null = new node;node::node(int x) { val = x, key = rand(), sz = 1, ch[0] = ch[1] = null; }struct Treap {    node* root;    Treap() { root = null; }    void rotate(node*& t, bool d) {        node* p = t->ch[d];        t->ch[d] = p->ch[!d];        p->ch[!d] = t;        t->update(), p->update();        t = p;    }    void insert(node*& t, int x) {        if (t == null) { t = new node(x); return; }        bool dir = x > t->val;        insert(t->ch[dir], x);        if (t->ch[dir]->key < t->key) rotate(t, dir);        else t->update();    }    void insert(int x) { insert(root, x); }    void mergeto(node*& t, Treap* tr) {        if (t->ch[0] != null) mergeto(t->ch[0], tr);        if (t->ch[1] != null) mergeto(t->ch[1], tr);        tr->insert(t->val);        delete t; t = null;    }    void mergeto(Treap* tr) { mergeto(root, tr); }    int calckth(int k) {        if (k <= 0 || k > root->sz) return INT_MIN;        bool dir;        for (node* t = root; t != null; t = t->ch[dir]) {            int cnt = t->ch[0]->sz;            if (k == cnt+1) return t->val;            else if (k <= cnt) dir = 0;            else dir = 1, k -= (cnt+1);        }    }}**treap = new Treap*[maxn];int find(int x) { return fa[x] == x ? x : fa[x] = find(fa[x]); }void unionn1(int& x, int& y) {    x = find(x), y = find(y);    if (x == y) return;    if (sz[x] > sz[y]) swap(x, y);    fa[x] = y; sz[y] += sz[x];}void unionn2(int x, int y) {    unionn1(x, y);    treap[x]->mergeto(treap[y]);}int n, m, q;void work() {    for (int i = 1; i <= n; ++i) {        scanf("%d", &val[i]);        mp[val[i]] = i;    }    for (int i = 1; i <= n; ++i) fa[i] = i, sz[i] = 1;    for (int i = 0; i < m; ++i) {        int u, v;        scanf("%d%d", &u, &v);        unionn1(u, v);    }    for (int i = 1; i <= n; ++i) {        treap[i] = new Treap();        fa[i] = find(i);    }    for (int i = 1; i <= n; ++i) {        treap[fa[i]]->insert(val[i]);    }    scanf("%d", &q);    while (q--) {        char c; int x, y;        scanf("\n%c%d%d", &c, &x, &y);        if (c == 'Q') {            int ans = treap[find(x)]->calckth(y);            printf("%d\n", ans == INT_MIN ? -1 : mp[ans]);        }        else unionn2(x, y);    }}int main() {    while (scanf("%d%d", &n, &m) != EOF) work();    return 0;}