hdu 5360 贪心+优先队列

贪心的思路还是比较好想的，每次选择cur（已经邀请成功的人数）所在的区间中右端点最小的（因为右端点大的在后面可以邀请成功的几率大），然后很自然的想到可以用一个优先队列来维护这些区间，只要每次把左端点小于等于cur的区间放到优先队列中即可。

 1 #include <iostream>
 2 #include <cstring>
 3 #include <cstdio>
 4 #include <vector>
 5 #include <queue>
 6 using namespace std;
 7
 8 const int N = 100001;
 9 bool visit[N];
10 int a[N];
11
12 struct Node
13 {
14     int r, id;
15     Node(){}
16     Node( int _r, int _id )
17     {
18         r = _r, id = _id;
19     }
20     bool operator < ( const Node & o ) const
21     {
22         return r > o.r;
23     }
24 };
25
26 vector<Node> v[N];
27 priority_queue<Node> q;
28
29 int main ()
30 {
31     int t;
32     scanf("%d", &t);
33     while ( t-- )
34     {
35         int n;
36         scanf("%d", &n);
37         for ( int i = 0; i <= n; i++ )
38         {
39             v[i].clear();
40         }
41         for ( int i = 1; i <= n; i++ )
42         {
43             scanf("%d", a + i);
44         }
45         for ( int i = 1; i <= n; i++ )
46         {
47             int tmp;
48             scanf("%d", &tmp);
49             v[a[i]].push_back( Node( tmp, i ) );
50         }
51         memset( visit, 0, sizeof(visit) );
52         int cur = 0, cnt = 1;
53         while ( 1 )
54         {
55             for ( int i = 0; i < v[cur].size(); i++ )
56             {
57                 q.push(v[cur][i]);
58             }
59             bool flag = false;
60             while ( !q.empty() )
61             {
62                 Node tt = q.top();
63                 q.pop();
64                 a[cnt++] = tt.id;
65                 visit[tt.id] = true;
66                 if ( tt.r >= cur )
67                 {
68                     cur++;
69                     flag = true;
70                     break;
71                 }
72             }
73             if ( !flag )
74             {
75                 break;
76             }
77         }
78         for ( int i = 1; i <= n; i++ )
79         {
80             if ( !visit[i] )
81             {
82                 a[cnt++] = i;
83             }
84         }
85         printf("%d\n", cur);
86         for ( int i = 1; i < n; i++ )
87         {
88             printf("%d ", a[i]);
89         }
90         printf("%d\n", a[n]);
91     }
92     return 0;
93 }