POJ_2010 Moo University - Financial Aid 【堆预处理】

 1 #include <cstdio>
 2 #include <algorithm>
 3 #include <queue>
 4 #include <fstream>
 5 #include <iostream>
 6 
 7 using namespace std;
 8 
 9 const int MAXN = 1e5+4;
10 int N, C, F, ans;
11 struct Node
12 {
13     int score, aid;
14     bool operator<(const Node t)const
15     {
16         return score < t.score;
17     }
18 }Calves[MAXN];
19 int Left[MAXN], Right[MAXN];
20 
21 void solve()
22 {
23     priority_queue<int, vector<int>, less<int> > pql, pqr;
24     int i, temp, sum = 0;
25     //正向扫描求最小和，保持大根堆的容量始终为N/2
26     for(i = 0; i < N/2; i++)
27     {
28         sum += Calves[i].aid;
29         Left[i] = 0;
30         pql.push(Calves[i].aid);
31     }
32     for(i; i < C-N/2; i++)
33     {
34         Left[i] = sum;
35         temp = pql.top();
36         if(Calves[i].aid < temp)
37         {
38             pql.pop();
39             sum -= temp;
40             sum += Calves[i].aid;
41             pql.push(Calves[i].aid);
42         }
43     }
44 
45     //反向扫描
46     sum = 0;
47     for(i = C-1; i > C-N/2-1; i--)
48     {
49          sum += Calves[i].aid;
50          Right[i] = 0;
51          pqr.push(Calves[i].aid);
52     }
53     for(i; i >= N/2; i--)
54     {
55         Right[i] = sum;
56         temp = pqr.top();
57         if(Calves[i].aid < temp)
58         {
59             pqr.pop();
60             sum -= temp;
61             sum += Calves[i].aid;
62             pqr.push(Calves[i].aid);
63         }
64     }
65 
66 }
67 
68 int main()
69 {
70     // freopen("input.txt", "r", stdin);
71     // freopen("out.txt", "w", stdout);
72     while(scanf("%d %d %d", &N, &C, &F)!=EOF)
73     {
74         bool flag = false;
75         for(int i = 0; i < C; i++)
76         {
77             scanf("%d %d", &Calves[i].score, &Calves[i].aid);
78         }
79         sort(Calves, Calves+C);
80         solve();
81         for(int i = C-N/2-1; i >= N/2; i--)
82         {
83             if(Right[i] + Left[i] + Calves[i].aid <= F)
84             {
85                 printf("%d\n", Calves[i].score);
86                 flag = true;
87                 break;
88             }
89         }
90         if(!flag)
91         {
92             printf("-1\n");
93         }
94     }
95     return 0;
96 }