王道数据结构p149——9

#include
#include
typedef struct treenode{
	char data;
	struct treenode *lchild,*rchild;
}treenode,*tree;

//ABD##E##C##    //ABD##E##CF##G##
void create(tree &t);
void swap(tree &t);
void printtree(tree t);

int main(){
	tree T;
	//stack s;
	create(T);
	swap(T);
	printtree(T);
	return 0;
} 
void swap(tree &t){
	if(t){
		if(t->lchild || t->rchild){
			treenode *p;
			p = t->lchild;
			t->lchild = t->rchild;
			t->rchild = p;
		} 
		swap(t->lchild);
		swap(t->rchild);
	}
}
void printtree(tree t){
	if(t){
		printf("%c  ",t->data);
		printtree(t->lchild);
		printtree(t->rchild);
	}
}
void create(tree &t){
	char c;
	c = getchar();
	if(c == '#') t = NULL;
	else{
		t = (treenode*)malloc(sizeof(treenode));
		t->data = c;
		t->lchild = NULL;
		t->rchild = NULL;
		create(t->lchild);
		create(t->rchild);
	}
}

注：这到题就是基于上一题进行部分修改即可