王道数据结构p149——10

#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 find_k(tree &t,int k);
void printtree(tree t);

int i = 0;

int main(){
	tree T;
	create(T);
	int k = 5;
	find_k(T,k);

	
	//printtree(T);
	return 0;
} 
void find_k(tree &t,int k){
	if(t){
		i++;
		if(k == i) printf("%c ",t->data);
		find_k(t->lchild,k);
		find_k(t->rchild,k);
	}
}

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，要添加一个全局变量i，通过i与k的比较，实现输出