Splay树求第k大模板

今天上午借着休息日得机会手撸了一下模板，终于对着模板调出来了。prev和next占用了std namespace里面的东西，然后报警我上次给关了所以。。。。。就花了3个小时吧。

inline加不加无所谓，但是代码规范一定要有。

#include <bits/stdc++.h>
using namespace std;
#define limit (1000000 + 5)//防止溢出
#define INF 0x3f3f3f3f
#define inf 0x3f3f3f3f3f
#define lowbit(i) i&(-i)//一步两步
#define EPS 1e-6
#define FASTIO  ios::sync_with_stdio(false);cin.tie(0);
#define ff(a) printf("%d\n",a );
#define pi(a,b) pair<a,b>
#define rep(i, a, b) for(ll i = a; i <= b ; ++i)
#define per(i, a, b) for(ll i = b ; i >= a ; --i)
#define MOD 998244353
#define traverse(u) for(int i = head[u]; ~i ; i = edge[i].next)
#define FOPEN freopen("C:\\Users\\tiany\\CLionProjects\\acm_01\\data.txt", "rt", stdin)
#define FOUT freopen("C:\\Users\\tiany\\CLionProjects\\acm_01\\dabiao.txt", "wt", stdout)
#define debug(x) cout<<x<<endl
typedef long long ll;
typedef unsigned long long ull;
inline ll read(){
    ll sign = 1, x = 0;char s = getchar();
    while(s > '9' || s < '0' ){if(s == '-')sign = -1;s = getchar();}
    while(s >= '0' && s <= '9'){x = (x << 3) + (x << 1) + s - '0';s = getchar();}
    return x * sign;
}//快读
void write(ll x){
    if(x < 0) putchar('-'),x = -x;
    if(x / 10) write(x / 10);
    putchar(x % 10 + '0');
}
struct node{
    node *son[2], *fa;//确定三个最重要的
    int key,cnt,size;
    node():fa(nullptr),key(0),cnt(0),size(0){
        son[0] = son[1] = nullptr;
    }

    bool get(){
        return fa->son[1] == this;
    }
    void update(){
        size = son[1]->size + son[0]->size + cnt;
    }
    void clear(){
        key = cnt = size = 0;
    }
}tree[limit],*root,*null;
int n,tot;
node* make_tree_node(){
    ++tot;
    tree[tot].son[0] = tree[tot].son[1] = tree[tot].fa = null;
    return &tree[tot];
}
inline void rotate(node *cur){
    node *fa = cur->fa,*grandfather = fa->fa;
    int rt = cur->get(), rt2 = fa->get();
    fa->son[rt] = cur->son[rt ^ 1];
    fa->son[rt]->fa = fa;
    cur->son[rt ^ 1] = fa;
    fa->fa = cur;
    cur->fa = grandfather;
    if(grandfather != null)
        grandfather->son[rt2] = cur;
    fa->update();
    cur->update();
}
inline void splay(node *cur){
    for(node *fa = null ;(fa=cur->fa) != null;rotate(cur)) {
        if (fa->fa != null) {
            rotate((fa->get() == cur->get()) ? fa : cur);
        }
    }
    root = cur;
}
inline void insert(int x){
    if(root == null){
        root = make_tree_node();
        root->key = x;
        root->cnt = root->size = 1;
        return;
    }

    for(node *cur = root,*fa = null; ; ){
        if(x == cur->key){
            cur->cnt++;
            splay(cur);
            return;
        }
        fa = cur;
        cur = cur->son[x > cur->key];
        if(cur == null){
            fa->son[x > fa->key]= cur = make_tree_node();
            cur->key = x;
            cur->cnt=1;
            cur->fa=fa;
            splay(cur);
            return;
        }
    }
}
int kth(int k){
    //求解k大
    for(node * cur = root;;){
        if(cur->son[0] != null && k <= cur->son[0]->size){
            cur = cur->son[0];
        }else{
            int left_size = cur->son[0]->size + cur->cnt;
            if(k <= left_size)return cur->key;
            k -= left_size;
            cur = cur->son[1];
        }
    }
}
int rank(int x){
    int ans = 0;
    for(node * cur = root; ; ){
        if(cur->son[0] != null && x < cur->key)cur = cur->son[0];
        else{
            ans += cur->son[0]->size;
            if(cur->key == x){
                splay(cur);
                return ans;
            }
            ans += cur->cnt;
            cur = cur->son[1];
        }
    }
}
node * pre(){//前驱
    node * cur = root->son[0];
    for(;cur->son[1] != null;cur = cur->son[1]);
    return cur;
}
void del(int x){
    ::rank(x);
    if(root->cnt > 1){
        root->cnt--;
        root->update();
        return;
    }
    node * l = pre(), *oldroot = root;
    splay(l);
    l->son[1] = oldroot->son[1];
    l->son[1]->fa = l;
    oldroot->clear();
    root->update();
}
int prev(node * rt, int val){
    if(rt == null)return -INF;
    if(val > rt->key)return max(rt->key,::prev(rt->son[1],val));
    else return ::prev(rt->son[0],val);
}
int next(node * rt, int val){
    if(rt == null)return INF;
    if(val < rt->key)return min( rt->key,::next(rt->son[0],val));
    else return ::next(rt->son[1],val);
}
int main() {
#ifdef LOCAL
    FOPEN;
#endif
    tot = 0;
    null = root = &tree[0];
    n = read();
    insert(INF), insert(-INF);
    while (n--){
        int op = read(), x = read();
        if(op == 1){
            insert(x);
        }else if(op == 2){
            del(x);
        }else if(op == 3){
            ff(::rank(x));
        }else if(op == 4){
            ff(kth(x + 1));
        }else if(op == 5){
            ff(::prev(root, x));
        }else{
            ff(::next(root,x))
        }
    }
    return 0;
}

Splay Tree