逆波兰-中缀树 变换

#include < stdio.h >
#include < stdlib.h >

typedef  struct  treeNode  * ptr;
typedef treeNode tree;

typedef  struct  stackNode  * ptrStack;
typedef ptrStack stack;

struct  treeNode
{
   char element;
   ptr left;
   ptr right;
       } ;
      
struct  stackNode
{
   tree element;
   ptrStack next;
       } ;

tree polishToTree( char  exp[])  
{
     int i=0;
     stack s=creatStack();
     while(exp[i]!='\0')
     {
       if(exp[i]!='+'&&exp[i]!='-'&&exp[i]!='*'&&exp[i]!='/')
       {
          tree tmpTree=creatTree();
          tmpTree->element=exp[i];
          tmpTree->left=tmpTree->right=NULL;
          push(tmpTree,s);
       }
       else
       {
           tree tmpTree=creatTree();
           tmpTree->element=exp[i];
           tmpTree->right=top(s);
           pop(s);
           tmpTree->left=top(s);
           pop(s);
           push(tmpTree,s);
       }
       i++;
     }
     tree result=top(s)->element;
     pop(s);
     return result;
}