The kth great number multiset应用（找第k大值）

Posted 2020-09-29 博客就叫Molex好了

The kth great number

 

Xiao Ming and Xiao Bao are playing a simple Numbers game. In a round Xiao Ming can choose to write down a number, or ask Xiao Bao what the kth great number is. Because the number written by Xiao Ming is too much, Xiao Bao is feeling giddy. Now, try to help Xiao Bao.

InputThere are several test cases. For each test case, the first line of input contains two positive integer n, k. Then n lines follow. If Xiao Ming choose to write down a number, there will be an " I" followed by a number that Xiao Ming will write down. If Xiao Ming choose to ask Xiao Bao, there will be a "Q", then you need to output the kth great number. 
OutputThe output consists of one integer representing the largest number of islands that all lie on one line. 
Sample Input

8 3
I 1
I 2
I 3
Q
I 5
Q
I 4
Q

Sample Output

1
2
3


        
 

Hint

Xiao  Ming  won‘t  ask  Xiao  Bao  the  kth  great  number  when  the  number  of  the  written number is smaller than k. (1=<k<=n<=1000000).



开一个multiset（允许存在相同值的集合且加入后自动排序），维护k个元素，多出在头部删除，最后取第一个元素即可,适用于找第几大第几小的题。

#include<stdio.h>
#include<set>
using namespace std;
int main()
{
    int n,k,x,i;
    char c;
    while(~scanf("%d%d",&n,&k)){
        multiset<int> a;
        for(i=1;i<=n;i++){
            getchar();
            scanf("%c",&c);
            if(c==‘I‘){
                scanf("%d",&x);
                a.insert(x);
                if(a.size()>k) a.erase(a.begin());
            }
            else printf("%d\n",*a.begin());
        }
    }
    return 0;
}