中级-day7作业

Description

读取字符串abcdefghij，然后层次建树建立一颗二叉树，然后前序遍历输出abdhiejcfg，注意不要打印前序遍历几个汉字

Input

abcdefghij

Output

abdhiejcfg

Sample Input 1 

abcdefghij

Sample Output 1

abdhiejcfg

#define _CRT_SECURE_NO_WARNINGS
#include 
#include 

typedef char BiElemtype;
typedef struct BiTNode {
	BiElemtype c;
	struct BiTNode* lchild;
	struct BiTNode* rchild;
}BiTNode,*BiTree;
typedef struct tag {
	BiTree p;
	struct tag* pnext;
}tag_t,*ptag_t;

void PreOrder(BiTree p) {
	if (NULL != p) {
		putchar(p->c);
		PreOrder(p->lchild);
		PreOrder(p->rchild);
	}
}

int main()
{
	BiTree tree = NULL;
	BiTree pnew;
	ptag_t phead = NULL;
	ptag_t ptail = NULL;
	ptag_t pcur = NULL;
	ptag_t listpnew;
	char c;
	while (scanf("%c", &c) != EOF) {
		if (c=='n') {
			break;
		}
		pnew = (BiTree)calloc(1, sizeof(BiTNode));
		pnew->c = c;
		listpnew = (ptag_t)calloc(1, sizeof(tag));
		listpnew->p = pnew;
		if (tree == NULL) {
			tree = pnew;
			pcur = phead = ptail = listpnew;
			continue;
		}
		else {
			ptail->pnext = listpnew;
			ptail = listpnew;
		}
		if (NULL == pcur->p->lchild) {
			pcur->p->lchild = pnew;
		}
		else if(NULL == pcur->p->rchild) {
			pcur->p->rchild = pnew;
			pcur = pcur->pnext;
		}
	}
	PreOrder(tree);
}