uva 442 - Matrix Chain Multiplication

表示从今以后要好好学习，代码写的太烂了

题目大意是求最少的计算次数，唉。。。

最大收获是学会了求表达式中各部分的优先级

  
    

   
     #include
   
     <
   
     stdio.h
   
     >
   
     
#include
   
     <
   
     stdlib.h
   
     >
   
     
typedef 
   
     struct
   
      _matrix
{
 
   
     char
   
      c;
 
   
     int
   
      row;
 
   
     int
   
      col;
 
   
     int
   
      rank;
 
   
     struct
   
      _matrix 
   
     *
   
     next;
 
   
     struct
   
      _matrix 
   
     *
   
     last;
}matrix;
matrix symbol[
   
     30
   
     ];

   
     char
   
      s[
   
     200
   
     ];

   
     char
   
      
   
     *
   
     _s;

   
     int
   
      i,n,rank,first,error,sum,max;
matrix 
   
     *
   
     head,
   
     *
   
     now,
   
     *
   
     p,
   
     *
   
     _p,
   
     *
   
     pp,
   
     *
   
     end;

   
     void
   
      getsum()
{
 error
   
     =
   
     0
   
     ;
 
   
     for
   
     (i
   
     =
   
     max;i
   
     >=
   
     0
   
     &&
   
     head
   
     ->
   
     next
   
     !=
   
     NULL;i
   
     --
   
     )
 {
 p
   
     =
   
     head;
 
   
     while
   
     (p
   
     ->
   
     rank
   
     !=
   
     i
   
     &&
   
     p
   
     !=
   
     NULL)
 p
   
     =
   
     p
   
     ->
   
     next;
 
   
     if
   
     (p
   
     ->
   
     next
   
     ==
   
     NULL
   
     ||
   
     p
   
     ->
   
     rank
   
     !=
   
     p
   
     ->
   
     next
   
     ->
   
     rank)
 {
 p
   
     ->
   
     rank
   
     --
   
     ;
 
   
     continue
   
     ;
 }
 
 
   
     while
   
     (p
   
     ->
   
     next
   
     !=
   
     NULL
   
     &&
   
     p
   
     ->
   
     rank
   
     ==
   
     p
   
     ->
   
     next
   
     ->
   
     rank)
 {
 
   
     if
   
     (p
   
     ->
   
     col
   
     !=
   
     p
   
     ->
   
     next
   
     ->
   
     row)
 {
 error
   
     =
   
     1
   
     ;
 
   
     break
   
     ;
 }
 sum
   
     +=
   
     (p
   
     ->
   
     row)
   
     *
   
     (p
   
     ->
   
     col)
   
     *
   
     (p
   
     ->
   
     next
   
     ->
   
     col);


 now
   
     =
   
     (matrix 
   
     *
   
     )malloc(
   
     sizeof
   
     (matrix));
 now
   
     ->
   
     row
   
     =
   
     p
   
     ->
   
     row;
 now
   
     ->
   
     col
   
     =
   
     p
   
     ->
   
     next
   
     ->
   
     col;
 now
   
     ->
   
     rank
   
     =
   
     p
   
     ->
   
     rank;

 _p
   
     =
   
     p
   
     ->
   
     last;
 pp
   
     =
   
     p
   
     ->
   
     next
   
     ->
   
     next;
 
   
     if
   
     (head
   
     ->
   
     next
   
     ->
   
     next
   
     ==
   
     NULL)
 {
 free(p
   
     ->
   
     next);
 free(p);
 head
   
     =
   
     now;
 head
   
     ->
   
     next
   
     =
   
     NULL;
 p
   
     =
   
     head;
 
   
     break
   
     ;
 }
 
   
     else
   
      
   
     if
   
     (p
   
     ==
   
     head)
 {
 head
   
     =
   
     now;
 now
   
     ->
   
     next
   
     =
   
     pp;
 pp
   
     ->
   
     last
   
     =
   
     now;
 head
   
     ->
   
     last
   
     =
   
     NULL;
 }
 
   
     else
   
      
   
     if
   
     (p
   
     ->
   
     next
   
     ==
   
     end)
 {
 end
   
     =
   
     now;
 end
   
     ->
   
     next
   
     =
   
     NULL;
 _p
   
     ->
   
     next
   
     =
   
     now;
 now
   
     ->
   
     last
   
     =
   
     _p;
 }
 
   
     else
   
     
 {
 _p
   
     ->
   
     next
   
     =
   
     now;
 now
   
     ->
   
     next
   
     =
   
     pp;
 pp
   
     ->
   
     last
   
     =
   
     now;
 now
   
     ->
   
     last
   
     =
   
     _p;
 }
 free(p
   
     ->
   
     next);
 free(p);
 p
   
     =
   
     now;
 }
 now
   
     ->
   
     rank
   
     --
   
     ;
 
   
     if
   
     (error)
 
   
     break
   
     ;
 }
}

   
     int
   
      main()
{
 scanf(
   
     "
   
     %d
   
     "
   
     ,
   
     &
   
     n);
 
   
     for
   
     (i
   
     =
   
     0
   
     ;i
   
     <
   
     n;i
   
     ++
   
     )
 {
 getchar();
 scanf(
   
     "
   
     %c%d%d
   
     "
   
     ,
   
     &
   
     symbol[i].c,
   
     &
   
     symbol[i].row,
   
     &
   
     symbol[i].col);
 }
 getchar();
 
   
     while
   
     (gets(s))
 {
 _s
   
     =
   
     s;
 rank
   
     =
   
     0
   
     ;
 first
   
     =
   
     1
   
     ;
 max
   
     =
   
     0
   
     ;
 sum
   
     =
   
     0
   
     ;
 
   
     while
   
     (
   
     *
   
     _s)
 {
 
   
     if
   
     (
   
     *
   
     _s
   
     ==
   
     '
   
     (
   
     '
   
     )
 {
 rank
   
     ++
   
     ;
 
   
     if
   
     (rank
   
     >
   
     max)
 max
   
     =
   
     rank;
 }
 
   
     else
   
      
   
     if
   
     (
   
     *
   
     _s
   
     ==
   
     '
   
     )
   
     '
   
     )
 {
 rank
   
     --
   
     ;
 
   
     if
   
     (
   
     *
   
     (_s
   
     +
   
     1
   
     )
   
     ==
   
     '
   
     (
   
     '
   
     )
 {
 getsum();
 
   
     if
   
     (error)
 
   
     break
   
     ;
 head
   
     ->
   
     rank
   
     =
   
     0
   
     ;
 rank
   
     =
   
     0
   
     ;
 max
   
     =
   
     0
   
     ;
 first
   
     =
   
     2
   
     ;
 }
 }
 
   
     else
   
     
 {
 now
   
     =
   
     (matrix 
   
     *
   
     )malloc(
   
     sizeof
   
     (matrix));
 
   
     for
   
     (i
   
     =
   
     0
   
     ;
   
     *
   
     _s
   
     !=
   
     symbol[i].c;i
   
     ++
   
     );
 now
   
     ->
   
     c
   
     =*
   
     _s;
 now
   
     ->
   
     rank
   
     =
   
     rank;
 now
   
     ->
   
     row
   
     =
   
     symbol[i].row;
 now
   
     ->
   
     col
   
     =
   
     symbol[i].col;
 
   
     if
   
     (first
   
     ==
   
     1
   
     )
 {
 head
   
     =
   
     now;
 head
   
     ->
   
     next
   
     =
   
     NULL;
 head
   
     ->
   
     last
   
     =
   
     NULL;
 p
   
     =
   
     head;
 end
   
     =
   
     p;
 first
   
     =
   
     0
   
     ;
 }
 
   
     else
   
     
 {
 now
   
     ->
   
     last
   
     =
   
     p;
 p
   
     ->
   
     next
   
     =
   
     now;
 p
   
     =
   
     now;
 end
   
     =
   
     p;
 p
   
     ->
   
     next
   
     =
   
     NULL;
 }
 }
 _s
   
     ++
   
     ;
 }
 getsum();
 
   
     if
   
     (error)
 printf(
   
     "
   
     error\n
   
     "
   
     );
 
   
     else
   
     
 printf(
   
     "
   
     %d\n
   
     "
   
     ,sum);
 }
 
   
     return
   
      
   
     0
   
     ;
}