树堆

Treap

洛谷 P3369 【模板】普通平衡树

#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using p = pair<int, int>;
const int maxn(1e5 + 10);
const int inf(0x3f3f3f3f);
int idx, root;

struct node {
    int l, r;
    int key, val;
    int cnt, siz;
} 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 new_node(int key)
{
    ++idx;
    tree[idx].key = key;
    tree[idx].val = rand();
    tree[idx].cnt = tree[idx].siz = 1;
    return idx;
}

inline void push_up(int cur)
{
    tree[cur].siz = tree[tree[cur].l].siz + tree[tree[cur].r].siz + tree[cur].cnt;
}

inline void zig(int& cur)
{
    int ls = tree[cur].l;
    tree[cur].l = tree[ls].r;
    tree[ls].r = cur;
    cur = ls;
    push_up(tree[cur].r);
    push_up(cur);
}

inline void zag(int& cur)
{
    int rs = tree[cur].r;
    tree[cur].r = tree[rs].l;
    tree[rs].l = cur;
    cur = rs;
    push_up(tree[cur].l);
    push_up(cur);
}

void build()
{
    root = new_node(-inf);
    tree[root].r = new_node(inf);
    push_up(root);
    if (tree[root].val < tree[tree[root].r].val) {
        zag(root);
    }
}

inline void insert(int& cur, int key)
{
    if (not cur) {
        cur = new_node(key);
    } else if (key == tree[cur].key) {
        ++tree[cur].cnt;
    } else if (key < tree[cur].key) {
        insert(tree[cur].l, key);
        if (tree[tree[cur].l].val > tree[cur].val) {
            zig(cur);
        }
    } else {
        insert(tree[cur].r, key);
        if (tree[tree[cur].r].val > tree[cur].val) {
            zag(cur);
        }
    }
    push_up(cur);
}

inline void remove(int& cur, int key)
{
    if (not cur) return;
    if (key == tree[cur].key) {
        if (tree[cur].cnt > 1) {
            --tree[cur].cnt;
        } else if (tree[cur].l or tree[cur].r) {
            if (not tree[cur].r or tree[tree[cur].l].val > tree[tree[cur].r].val) {
                zig(cur);
                remove(tree[cur].r, key);
            } else {
                zag(cur);
                remove(tree[cur].l, key);
            }
        } else {
            cur = 0;
        }
    } else if (key < tree[cur].key) {
        remove(tree[cur].l, key);
    } else {
        remove(tree[cur].r, key);
    }
    push_up(cur);
}

inline int get_rank(int cur, int key)
{
    if (not cur) {
        return 0;
    }
    if (key == tree[cur].key) {
        return tree[tree[cur].l].siz + 1;
    }
    if (key < tree[cur].key) {
        return get_rank(tree[cur].l, key);
    }
    return get_rank(tree[cur].r, key) + tree[tree[cur].l].siz + tree[cur].cnt;
}

inline int get_key(int cur, int rank)
{
    if (not cur) {
        return inf;
    }
    if (rank <= tree[tree[cur].l].siz) {
        return get_key(tree[cur].l, rank);
    }
    if (rank <= tree[tree[cur].l].siz + tree[cur].cnt) {
        return tree[cur].key;
    }
    return get_key(tree[cur].r, rank - tree[cur].cnt - tree[tree[cur].l].siz);
}

inline int get_prev(int cur, int key)
{
    if (not cur) {
        return -inf;
    }
    if (key <= tree[cur].key) {
        return get_prev(tree[cur].l, key);
    }
    return max(tree[cur].key, get_prev(tree[cur].r, key));
}

inline int get_next(int cur, int key)
{
    if (not cur) {
        return inf;
    }
    if (key >= tree[cur].key) {
        return get_next(tree[cur].r, key);
    }
    return min(tree[cur].key, get_next(tree[cur].l, key));
}

int main()
{
#ifdef ONLINE_JUDGE
#else
    freopen("input.txt", "r", stdin);
#endif
    build();
    int n = read();
    while (n--) {
        int op = read(), x = read();
        if (op == 1) {
            insert(root, x);
        } else if (op == 2) {
            remove(root, x);
        } else if (op == 3) {
            write(get_rank(root, x) - 1, true);
        } else if (op == 4) {
            write(get_key(root, x + 1), true);
        } else if (op == 5) {
            write(get_prev(root, x), true);
        } else {
            write(get_next(root, x), true);
        }
    }
    return 0;
}