Description

P2343 宝石管理系统

Solution

无旋treap \(（fhq-treap）\)

洛谷模板题简化版。

不多说了。

有不会的话看我的博客吧。

浅谈 fhq-treap（无旋treap）

有一个小坑点，题目中求的是第 \(n\) 大的数是多少，所以查询时要查 \(tot - n + 1\) （\(tot\) 是总结点数）。

Code

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstdlib>
#define ls(x) t[x].ch[0]
#define rs(x) t[x].ch[1]

using namespace std;

const int N = 2e5 + 10;
struct Tree{
	int ch[2], val, siz, wei;
}t[N];
int n, m, tot, root;
int a, b, c;

inline int read(){
	int 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;
}

inline void pushup(int x){
	t[x].siz = t[ls(x)].siz + t[rs(x)].siz + 1;
}

inline void split(int x, int k, int &a, int &b){
	if(!x){
		a = b = 0;
		return;
	}
	if(t[x].val <= k){
		a = x;
		split(rs(x), k, rs(x), b);
	}else{
		b = x;
		split(ls(x), k, a, ls(x));
	}
	pushup(x);
}

inline int merge(int x, int y){
	if(!x || !y) return x + y;
	if(t[x].wei <= t[y].wei){
		rs(x) = merge(rs(x), y);
		pushup(x);
		return x;
	}else{
		ls(y) = merge(x, ls(y));
		pushup(y);
		return y;
	}
}

inline void insert(int k){
	t[++tot].val = k, t[tot].siz = 1, t[tot].wei = rand();
	split(root, k, a, b);
	root = merge(merge(a, tot), b);
}

inline int check_val(int x, int k){
	if(k == t[ls(x)].siz + 1) return t[x].val;
	if(k <= t[ls(x)].siz) return check_val(ls(x), k);
	else return check_val(rs(x), k - t[ls(x)].siz - 1);
}

int main(){
	n = read(), m = read();
	for(int i = 1; i <= n; i++){
		int x = read();
		insert(x);
	}
	for(int i = 1; i <= m; i++){
		int op = read(), x = read();
		if(op == 1) printf("%d\n", check_val(root, tot - x + 1));
		else insert(x);
	}
	return 0;
}

End