HDU 4006 The kth great number

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

The kth great number

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65768/65768 K (Java/Others)

Total Submission(s): 9731    Accepted Submission(s): 3873

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 3I 1I 2I 3QI 5QI 4Q

 

Sample Output

123
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).
 

 

Source

The 36th ACM/ICPC Asia Regional Dalian Site —— Online Contest

 

Recommend

lcy

思路：优先队列的应用。因为k不会变，所以只要用优先队列维护k个数为最大的k个数即可，重载一下小于运算符，让第k大数总是在队首，那么新来的数只要和它比即可，大于就删除队首，插入新数，否则不插入。

附上AC代码：

#include <bits/stdc++.h>//#pragma comment(linker, "/STACK:102400000, 102400000")using namespace std;struct node{int num;bool operator < (const node & p) const {return num > p.num;}};priority_queue<node> q;int n, k;int main(){#ifdef LOCALfreopen("input.txt", "r", stdin);freopen("output.txt", "w", stdout);#endifwhile (~scanf("%d%d", &n, &k)){while (!q.empty())q.pop();char op[5];node t;while (n--){scanf("%s", op);if (op[0] == 'I'){scanf("%d", &t.num);if (q.size() < k)q.push(t);else if (t.num > q.top().num){q.pop();q.push(t);}}elseprintf("%d\n", q.top().num);}}return 0;}