HDOJ 4006The kth great number 解题报告

链接：http://acm.hdu.edu.cn/showproblem.php?pid=4006

Problem Description

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.

Input

There 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. 

Output

The 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

考查优先队列，由于题目要找到第k大的数，所以构建个大小为k的优先队列，如果队列大小以达到k，再向队

列添加元素时将最小的元素移出队列。注意，队列默认是值大的先出列，所以用语句priority_queue<int,

vector<int>,greater<int> > q;定义优先队列，从而改变出队列的顺序。

#include<cstdio>#include<queue>#include<iostream>using namespace std;int main(){    int n,k,t;    char x;    int temp;    while(scanf("%d%d\n",&n,&k)!=EOF)    {        priority_queue<int,vector<int>,greater<int> > q;        for(t=1;t<=n;t++)        {        scanf("%c",&x);        if(x=='I')        {            scanf("%d\n",&temp);            if(q.size()<k) q.push(temp);            else            {                q.push(temp);                q.pop();            }        }        else{scanf("%c",&x);printf("%d\n",q.top());}        }    }}