ZOJ 1463 Brackets Sequence

区间DP，刘汝佳黑书p113例题

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <cstdlib>
 4 #include <algorithm>
 5 
 6 using namespace std;
 7 
 8 const int MAXN = 210;
 9 const int INF = 1 << 30;
10 
11 char str[MAXN];
12 int dp[MAXN][MAXN];
13 int path[MAXN][MAXN];
14 bool vis[MAXN][MAXN];
15 int len;
16 
17 inline bool check( char a, char b )
18 {
19     return (a == '(' && b == ')') || ( a == '[' && b == ']' );
20 }
21 
22 void PrintPath( int i, int j )
23 {
24     if ( i > j ) return;
25     if ( i == j )
26     {
27         if ( str[i] == '[' || str[i] == ']' )
28             printf( "[]" );
29         else printf( "()" );
30         return;
31     }
32     if ( path[i][j] == -1 )
33     {
34         putchar( str[i] );
35         PrintPath( i + 1, j - 1 );
36         putchar( str[j] );
37     }
38     else
39     {
40         PrintPath( i, path[i][j] );
41         PrintPath( path[i][j] + 1, j );
42     }
43 }
44 
45 void DP()
46 {
47     for ( int i = 1; i <= len; ++i ) dp[i][i - 1] = 0;
48     for ( int i = 1; i <= len; ++i ) dp[i][i] = 1;
49 
50     for ( int p = 1; p < len; ++p )
51     for ( int i = 1; i <= len - p; ++i )
52     {
53         int j = i + p;
54         dp[i][j] = INF;
55         if ( check( str[i], str[j] ) )
56         {
57             if ( dp[i + 1][j - 1] < dp[i][j] )
58             {
59                 dp[i][j] = dp[i + 1][j - 1];
60                 path[i][j] = -1;
61             }
62         }
63 
64         for ( int k = i; k < j; ++k )
65         {
66             if ( dp[i][k] + dp[k + 1][j] < dp[i][j] )
67             {
68                 dp[i][j] = dp[i][k] + dp[k + 1][j];
69                 path[i][j] = k;
70             }
71         }
72     }
73     return;
74 }
75 
76 int main()
77 {
78     int T;
79     bool flag = false;
80     scanf( "%d", &T );
81     getchar();
82     while ( T-- )
83     {
84         getchar();
85         gets( &str[1] );
86         len = strlen( &str[1] );
87         DP();
88         if ( flag ) putchar('\n');
89         PrintPath( 1, len );
90         putchar('\n');
91         flag = true;
92     }
93     return 0;
94 }

 

posted @ 2013-05-05 20:07  冰鸮  阅读(202)  评论(0)  编辑  收藏  举报