C语言实现:层次建立二叉树

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

typedef char ElemType;//为了树中放任意类型元素方便

typedef struct node_t
{//第一步:
	ElemType c;
	struct node_t *pright;
	struct node_t *pleft;
}Node_t, *pNode_t;
//queue[kju]
//辅助队列数据结构，每个元素放的树中元素节点地址值，能快速定树中节点
typedef struct queue_t{
	pNode_t insertPos;
	struct queue_t *pNext;
}Queue_t, *pQueue_t;

void preOrder(pNode_t);

void buildBinaryTree(pNode_t *treeRoot, pQueue_t *queHead, pQueue_t *queTail, ElemType val){
	pNode_t treeNew = (pNode_t)calloc(1, sizeof(Node_t));
	pQueue_t queNew = (pQueue_t)calloc(1,sizeof(Queue_t));
	pQueue_t queCur = *queHead;
	treeNew->c = val;
	queNew->insertPos = treeNew;
	if (NULL == *treeRoot){
		*treeRoot = treeNew;
		*queHead = queNew;
		*queTail = queNew;
	}
	else{
		(*queTail)->pNext = queNew; 
		*queTail = queNew;
		if (NULL == queCur->insertPos->pleft){
			queCur->insertPos->pleft = treeNew;
		}
		else if(NULL == queCur->insertPos->pright){//漏了if(NULL == queNew->insertPos->pright)
			queCur->insertPos->pright = treeNew;
			*queHead = queCur->pNext;
			free(queCur);
			queCur = NULL; 
		}
	}
}
int main(){
	ElemType val;
	pNode_t treeRoot = NULL;
	pQueue_t queHead = NULL, queTail = NULL;
	//写成   (scanf"%d",&val) != EOF
	//漏了eof
	while (scanf("%c", &val) != EOF ){ 
		if (val=='\n')
		{
			break;
		}
		buildBinaryTree(&treeRoot, &queHead, &queTail, val);
	}
	printf("前序打印:\n");
	preOrder(treeRoot);
}

void preOrder(pNode_t p){
	if (p != NULL)
	{
		putchar(p->c);
		preOrder(p->pleft);
		preOrder(p->pright);
	}
}