HDU 5087

DP找次最大最大子序列

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <cstdlib>
 4 #include <ctime>
 5 #include <cmath>
 6 #include <cctype>
 7 #include <string>
 8 #include <vector>
 9 #include <map>
10 #include <set>
11 #include <stack>
12 #include <algorithm>
13 #include <iostream>
14 using namespace std;
15 typedef long long ll;
16 const int NO = 1000 + 10;
17 vector <int> vis[NO];
18 int num[NO];
19 int dp[NO];
20 int n;
21 
22 inline bool dfs( int x )
23 {
24     if( vis[x].size() > 1 )
25         return true;
26     for( int i = 0; i < vis[x].size(); ++i )
27     {
28         bool flag = dfs( vis[x][i] );
29         if( flag )
30             return true;
31     }
32     return false;
33 }
34 
35 int main()
36 {
37     int T;
38     scanf( "%d", &T );
39     while( T-- )
40     {
41         scanf( "%d", &n );
42         for( int i = 0; i < n; ++i )
43             scanf( "%d", &num[i] );
44         int ans = 0, cur, Max = 0;
45         for( int i = 0; i < n; ++i )
46         {
47             vis[i].clear();
48             dp[i] = 1;
49             for( int j = 0; j < i; ++j )
50                 if( num[i] > num[j] )
51                 {
52                     if( dp[i] < dp[j] + 1 )
53                     {
54                         vis[i].clear();
55                          dp[i] = dp[j] + 1;
56                          vis[i].push_back( j );
57                     }
58                     else if( dp[i] == dp[j] + 1 )
59                         vis[i].push_back( j );
60                 }
61             if( Max < dp[i] )
62             {
63                 cur = i;
64                 ans =  1;
65                 Max = dp[i];
66             }
67             else if( Max == dp[i] )
68             {
69                 ++ans;
70                 cur = i;
71             }
72         }
73         if( ans > 1 )
74         {
75             printf( "%d\n", Max );
76             continue;
77         }
78         if( dfs( cur ) )
79             printf( "%d\n", Max );
80         else
81             printf( "%d\n", Max-1 );
82     }
83     return 0;
84 }

 

posted @ 2014-11-02 14:00  A_dan  阅读(183)  评论(0)  编辑  收藏  举报