题目来源：URAL 1439. Battle with You-Know-Who

题意：开始有数列1, 2, 3, ... L k输出第k大的数 D k删除第k大的数

思路：treap树插入删除的数 每次二分查找第k大的数为mid 查询treap小于等于mid的数有y个 那么mid应该是第mid-y大的数 与k比较 继续二分

#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>
using namespace std;

const int maxm = 100010;
int ch[maxm][2], r[maxm], val[maxm], sum[maxm], num[maxm], cnt, root;

void Node(int &rt, int x){
    rt = ++cnt;
    ch[rt][0] = ch[rt][1] = 0;
    r[rt] = rand();
    val[rt] = x;
    if(cnt > 1)
    {
		sum[rt] = 1;
    	num[rt] = 1;
    }
    else
    {
    	sum[rt] = 0;
    	num[rt] = 0;
    }
} 
void maintain(int rt){
    
    sum[rt] = sum[ch[rt][0]]+sum[ch[rt][1]]+num[rt];
}
void init()
{
	ch[0][0] = ch[0][1] = 0;
	r[0] = (1LL<<31)-1;
	val[0] = 0;
	sum[0] = 0;
	cnt = 0;
	root = 0;
	Node(root, 2000000001);
}


void rotate(int &rt, int d){
    int k = ch[rt][d^1]; ch[rt][d^1] = ch[k][d]; ch[k][d] = rt;
    maintain(rt); maintain(k); rt = k;
}

void insert(int &rt, int x){
    if(!rt){
        Node(rt, x);
        return;
    }
    else{
        if(x == val[rt])
            num[rt]++;
        else
        {
            int d = x < val[rt] ? 0 : 1;
            insert(ch[rt][d], x);
            if(r[ch[rt][d]] < r[rt]) rotate(rt, d^1);
        }
    }
    maintain(rt);
}

/*void remove(int &rt, int x){
    if(val[rt] == x){
        val[rt]--;
        if(!val[rt]){
            if(!ch[rt][0] && !ch[rt][1])
            {
                rt = 0;
                return;
            }
            else{
                int d = r[ch[rt][0]] > r[ch[rt][1]] ? 1 : 0;
                rotate(rt, d);
                remove(ch[rt][d], x);
            }
            else{
                
            }
        }
    }
    else
        remove(ch[rt][x>val[rt]], x);
    maintain(rt);
}*/

int kth(int rt, int k){
    if(rt == 0)
    	return 0;
	if(val[rt] <= k)
		return sum[ch[rt][0]]+num[rt]+kth(ch[rt][1], k);
	return kth(ch[rt][0], k);
	
}

int main()
{
	int n, m;
    while(scanf("%d %d", &n, &m) != EOF)
    {    
    	init();
        while(m--)
        {
        	char s[10];
        	int x;
        	scanf("%s %d", s, &x);
        	int l = 1, r = n, ans;
        	//printf("****%d\n", kth(root, 10));
    		while(l < r)
        	{
        		int mid = (l + r) >> 1; 
				int y = kth(root, mid);
        		if(x > mid-y)
        		{
	        		l = mid+1;
	        		ans = mid+1;
	        	}
	        	else
	        	{
        			r = mid;
        		}
				//printf("***%d\n", y);
        	}
        	if(s[0] == 'L')
        	{
				printf("%d\n", l);	
	        }
	        else
        	{
        		//int y = kth(root, x);
				insert(root, l);
        	}
        }
    }
    return 0;
}

URAL 1439. Battle with You-Know-Who treap树