[洛谷P4291][HAOI2008]排名系统

题目大意：三种操作：

1. $+Name\;Socore：$上传最新得分记录，把以前的记录删除。
2. $?Name：$ 查询玩家排名。如果两个玩家的得分相同，则先得到该得分的玩家排在前面。
3. $?Index：$ 返回自第$Index$名开始的最多$10$名玩家名字。

题解：平衡树，支持删除，插入，查询第$k$名，查询一个玩家的排名。

卡点：新建节点时忘记赋$size$

C++ Code：

#include <cstdio>
#include <map>
#include <iostream>
#define maxn 250010
std::map<std::string, int> name;
int n, namenum;
struct node {
	int v, p;
	inline node(int __v = 0, int __p = 0) {v = __v, p = __p;}
	inline friend bool operator > (const node &lhs, const node &rhs) {
		if (lhs.v == rhs.v) return lhs.p < rhs.p;
		return lhs.v > rhs.v;
	}
	inline friend bool operator == (const node &lhs, const node &rhs) {return lhs.v == rhs.v && lhs.p == rhs.p;}
	inline friend bool operator >= (const node &lhs, const node &rhs) {return lhs > rhs || lhs == rhs;}
};

namespace Treap {
	int lc[maxn], rc[maxn], num[maxn], sz[maxn];
	node val[maxn];
	int root, idx;
	int ta, tb, tmp, res;
	int seed = 20040826;
	inline int rand() {return seed *= 48271;}

	inline int update(int rt) {
		sz[rt] = sz[lc[rt]] + sz[rc[rt]] + 1;
		return rt;
	}
	inline int nw(node x) {
		val[++idx] = x;
		num[idx] = rand();
		sz[idx] = 1;
		return idx;
	}
	void split(int rt, node k, int &x, int &y) {
		if (!rt) x = y = 0;
		else {
			if (val[rt] >= k) split(rc[rt], k, rc[rt], y), x = update(rt);
			else split(lc[rt], k, x, lc[rt]), y = update(rt);
		}
	}
	void split(int rt, int k, int &x, int &y) {
		if (!rt) x = y = 0;
		else {
			if (sz[lc[rt]] < k) split(rc[rt], k - sz[lc[rt]] - 1, rc[rt], y), x = update(rt);
			else split(lc[rt], k, x, lc[rt]), y = update(rt);
		}
	}
	int merge(int x, int y) {
		if (!x || !y) return x | y;
		if (num[x] < num[y]) {rc[x] = merge(rc[x], y); return update(x);}
		else {lc[y] = merge(x, lc[y]); return update(y);}
	}

	inline int gtrnk(node x) {
		split(root, x, ta, tb);
		res = sz[ta];
		root = merge(ta, tb);
		return res;
	}
	inline node gtkth(int k) {
		tmp = root;
		while (true) {
			if (sz[lc[tmp]] >= k) tmp = lc[tmp];
			else {
				if (sz[lc[tmp]] + 1 == k) return val[tmp];
				else k -= sz[lc[tmp]] + 1, tmp = rc[tmp];
			}
		}
	}

	void insert(node x) {
		if (!root) root = nw(x);
		else {
			split(root, x, ta, tb);
			root = merge(merge(ta, nw(x)), tb);
		}
	}
	void erase(node x) {
		split(root, x, ta, tb);
		split(ta, sz[ta] - 1, ta, tmp);
		root = merge(ta, tb);
	}
}

int val[maxn];
std::string retname[maxn];
int main() {
	scanf("%d", &n);
	for (int i = 1; i <= n; i++) {
		char op;
		std::string s;
		std::cin >> op >> s;
		if (op == '+') {
			int x;
			std::cin >> x;
			if (name.count(s)) {
				int pos = name[s];
				Treap::erase(node(val[pos], pos));
				namenum--;
			}
			namenum++;
			name[s] = i;
			retname[i] = s;
			val[i] = x;
			Treap::insert(node(x, i));
		} else if (isdigit(s[0])) {
			int pos = 0, posend;
			for (std::string::iterator it = s.begin(); it != s.end(); it++) pos = pos * 10 + (*it & 15);
			posend = std::min(pos + 9, namenum);
			for (int i = pos; i <= posend; i++) {
				std::cout << retname[Treap::gtkth(i).p];
				putchar(i == posend ? '\n' : ' ');
			}
		} else {
			int pos = name[s];
			std::cout << Treap::gtrnk(node(val[pos], pos)) << std::endl;
		}

	}
	return 0;
}