[DP] PKU 1141 括号序列

[DP] PKU 1141 括号序列

http://poj.org/problem?id=1141
DP, 记录路径。

# include  < stdio.h >
# include  < string .h >

# define N  205
# define INF  1000000000
# define Mid ( 1   <<   10 )
# define Lft ( 1   <<   9  )
# define Rgt ( 1   <<   8  )

char  buf[N];
int  f[N][N], p[N][N];

int  dp( int  x,  int  y)
{
                 int   &  ans  =  f[x][y];
                 if  (ans  !=   - 1 )  return  ans;
                 if  (x  >  y)  return  ans  =   0 ;
                ans  =  INF;
                 if  ( (buf[x] == ' ( ' && buf[y] == ' ) ' )  ||
                     (buf[x] == ' [ ' && buf[y] == ' ] ' ) )
                {
                                 if  (ans  >  dp(x + 1 , y - 1 ))
                                {
                                                p[x][y]  =  Mid;
                                                ans  =  f[x + 1 ][y - 1 ];
                                }
                }
                 if  ( buf[x] == ' ( '   ||  buf[x] == ' [ '  )
                {
                                 if  (ans  >  dp(x + 1 , y) + 1 )
                                {
                                                p[x][y]  =  Rgt;
                                                ans  =  f[x + 1 ][y]  +   1 ;
                                }
                }
                 if  ( buf[y] == ' ) '   ||  buf[y] == ' ] '  )
                {
                                 if  (ans  >  dp(x, y - 1 ) + 1 )
                                {
                                                p[x][y]  =  Lft;
                                                ans  =  f[x][y - 1 ]  +   1 ;
                                }
                }
                 for  ( int  i  =  x; i  <  y;  ++ i)
                {
                                 if  (ans  >  dp(x, i) + dp(i + 1 , y))
                                {
                                                p[x][y]  =  i;
                                                ans  =  f[x][i]  +  f[i + 1 ][y];
                                }
                }
                 return  ans;
}

void  print( int  s,  int  t)
{
                 switch (p[s][t])
                {
                                 case  Mid:
                                {
                                                putchar(buf[s]), print(s + 1 , t - 1 ), putchar(buf[t]);
                                                 break ;
                                }
                                 case  Lft:
                                {
                                                 if  (buf[t]  ==   ' ) ' )
                                                                putchar( ' ( ' ), print(s, t - 1 ), putchar( ' ) ' );
                                                 else
                                                                putchar( ' [ ' ), print(s, t - 1 ), putchar( ' ] ' );
                                                 break ;
                                }
                                 case  Rgt:
                                {
                                                 if  (buf[s]  ==   ' ( ' )
                                                                putchar( ' ( ' ), print(s + 1 , t), putchar( ' ) ' );
                                                 else
                                                                putchar( ' [ ' ), print(s + 1 , t), putchar( ' ] ' );
                                                 break ;
                                }
                                 case   0 :
                                {
                                                 for  ( int  i  =  s; i  <=  t;  ++ i)
                                                                putchar(buf[i]);
                                                 break ;
                                }
                                 default :
                                {
                                                print(s, p[s][t]), print(p[s][t] + 1 , t);
                                                 break ;
                                }
                }
}

int  main()
{
                 int  n;

                buf[ 0 ]  =   0 , scanf( " %s " , buf + 1 );
                memset(f,  - 1 ,  sizeof (f));
                memset(p,  0 ,  sizeof (p));
                n  =  strlen(buf + 1 );
                dp( 1 , n), print( 1 , n), putchar( ' \n ' );

                 return   0 ;
}