C :

#include <stdio.h>
#include <stdlib.h>
typedef struct TNode{
	char data;
	struct TNode *left,*right;
}TNode,*BTree;
int index=0;
char c[101];
void create(BTree *t){
	if (c[index]=='#'||c[index]==' ')
	{
		index++;
		*t=NULL;
	}else{
		*t=(TNode*)malloc(sizeof(TNode));
		(*t)->data=c[index];
		index++;
		create(&(*t)->left);
		create(&(*t)->right);
	}
}
void remove_tree(BTree t){
	if (t)
	{
		remove_tree(t->left);
		remove_tree(t->right);
		free(t);
	}
}
void inorder(BTree t){
	if (t)
	{
		inorder(t->left);
		printf("%c ",t->data);
		inorder(t->right);
	}
}
int main(){
	BTree t;
//	freopen("1.txt","r",stdin);
	while (scanf("%s",c)!=EOF)
	{
		index=0;
		create(&t);
		inorder(t);
		remove_tree(t);
		printf("\n");
	}
//	fclose(stdin);
	return 0;
}

C++ :

#include <stdio.h>
#include <stdlib.h>
 
char cache[101];
 
typedef struct Node
{
    char data;
    struct Node * lchild,* rchild;
};
struct Node * root;
int cnt;
 
struct Node * Build_tree()
{
    struct Node * root;
    if(cache[cnt++] == '#') root = NULL;
    else
    {
        root = (struct Node *)malloc(sizeof(struct Node));
        root -> data = cache[cnt - 1];
        root -> lchild = Build_tree();
        root -> rchild = Build_tree();
    }
    return root;
}
void in_order(struct Node *root)
{
    if(root != NULL)
    {
        in_order(root -> lchild);
        printf("%c ",root -> data);
        in_order(root -> rchild);
    }
}
void clean(struct Node *root)
{
    if(root != NULL)
    {
        clean(root -> lchild);
        clean(root -> rchild);
        free(root);
    }
}
int main()
{
    int i;
    while(scanf("%s",cache) != EOF)
    {
        cnt = 0;
        root = Build_tree();
        in_order(root);
        clean(root);
        printf("\n");
    }
    return 0;
}

Pascal :

program acmshuu;
type piont=^node;
     node=record
       left:piont;
       root:char;
       right:piont;
     end;
var n,ch:char;
zh:piont;

procedure init(zh:piont);
 var p:piont;
  begin
    read(ch);
    if ch='#' then zh^.left:=nil
     else
     begin
       new(p);
       zh^.left:=p;
       p^.root:=ch;
       init(p);
     end;
    read(ch);
    if ch='#' then zh^.right:=nil
     else
      begin
       new(p);
       zh^.right:=p;
       p^.root:=ch;
       init(p);
      end;
  end;

procedure bianli(zh:piont);
  begin
    if zh^.left<>nil then bianli(zh^.left);
    write(zh^.root,' ');
    if zh^.right<>nil then bianli(zh^.right);
  end;

begin
  while not eof do
    begin
      new(zh);
      read(n);
      zh^.root:=n;
      init(zh);
      readln;
      bianli(zh);
      writeln;
    end;
end.