POJ 2010

 1 #include <iostream>
 2 #include <algorithm>
 3 #include <queue>
 4 using namespace std;
 5  
 6 #define MAX_COW 100000 + 16
 7  
 8 int N, C, F;
 9 pair<int, int> cow[MAX_COW];
10 // 牛i作为中位数时，lower[i]表示分数低于它的牛的学费总和
11 int lower[MAX_COW], upper[MAX_COW];
12  
13 ///////////////////////////SubMain//////////////////////////////////
14 int main()
15 {
16     cin >> N >> C >> F;
17     int half = N / 2;
18     for (int i = 0; i < C; ++i)
19     {
20         cin >> cow[i].first >> cow[i].second;    // 分数 <-> 学费
21     }
22     sort(cow, cow + C);
23     {
24         int total = 0;
25         priority_queue<int> q;
26         for (int i = 0; i < C; ++i)
27         {
28             lower[i] = q.size() == half ? total : 0x3f3f3f3f;
29             q.push(cow[i].second);
30             total += cow[i].second;
31             if (q.size() > half)
32             {
33                 // 然后踢掉一个学费最高的家伙
34                 total -= q.top(); q.pop();
35             }
36         }
37     }
38  
39     {
40         int total = 0;
41         priority_queue<int> q;
42         for (int i = C - 1; i >= 0; --i)
43         {
44             upper[i] = q.size() == half ? total : 0x3f3f3f3f;
45             q.push(cow[i].second);
46             total += cow[i].second;
47             //思考之后发现要用优先队列
48             if (q.size() > half)
49             {
50                 // 然后踢掉一个学费最高的家伙
51                 total -= q.top(); q.pop();
52             }
53         }
54     }
55  
56     int result;
57     for (int i = C - 1; i >= 0; --i)
58     {
59         if (lower[i] + cow[i].second + upper[i] <= F)
60         {
61             result = cow[i].first;
62             break;
63         }
64     }
65  
66     cout << result << endl;
67 
68     return 0;
69 }