C++后序建立二叉树

#include "stdafx.h"
#include<iostream>
#include<stack>
using namespace std;
typedef struct binode {
	binode* lchild, *rchild;
	char data;
}binode,*bitree;

int aftorder_bitree_create(bitree &T) {
	stack<bitree>S;
	bitree Q,D;
	char ch = getchar();
	do {
		int k = 0;
		if (ch != '#'&&S.size()==0)exit(-1);
		while (ch== '#') {
			k++;
			ch = getchar();
		} ;
		switch (k) {
		case 0:
			if (S.size() > 1) {
				if (!(Q = new(nothrow)binode))exit(-1);
				if (!(D = new(nothrow)binode))exit(-1);
				D->data = ch;
				Q = S.top();
				S.pop();
				D->rchild = Q;
				Q = S.top();
				S.pop();
				D->lchild = Q; 
				S.push(D); 
		}
			else exit(-1); break;
		case 1:
			if (S.size()>0) {
				if (!(Q = new(nothrow)binode))exit(-1);
				if (!(D = new(nothrow)binode))exit(-1);
				Q = S.top();
				S.pop();
				D->lchild = Q;
				D->rchild = NULL;
				D->data = ch;
				S.push(D);
			}
			else exit(-1); break;
		default:
			Q=NULL;
			for (int i = 1; i < k; i++) {
				if (!(D = new(nothrow)binode))exit(-1);
				D->data = ch;
				D->lchild = NULL;
				D->rchild = Q;
				Q = D;
				if (i<k-1&&(ch = getchar()) == '#')exit(-1);
			}
			S.push(D);
			break;
		}
		ch = getchar();
	} while (ch != 10 || S.size() != 1);
	T = D;
	return 1;
}

int main()
{
	bitree T;
	if (!(T = new(nothrow)binode))exit(-1);
	aftorder_bitree_create(T);
	//input:##a###yxb#c#d###qp#o#ef
	getchar();
    return 0;
}