C :

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
char s[200],t[100];
int l[100],r[100];
int n,j,k;

void tree(int f,int p) {
	int i;
	j++;
    if (s[j]=='.') {if (f==0) l[p]=0;else r[p]=0;}
	else {
		k++;i=k;
		t[k]=s[j];
		if (f==0) l[p]=i;else r[p]=i;
		tree(0,i);
		tree(1,i);
	}
}

void tree_z(int i){
	if (l[i]>0) tree_z(l[i]);
	printf("%c",t[i]);
	if (r[i]>0) tree_z(r[i]);
}

void tree_h(int i){
	if (l[i]>0) tree_h(l[i]);
	if (r[i]>0) tree_h(r[i]);
	printf("%c",t[i]);
}

int main(){
	scanf("%s",s);
	n=strlen(s)-1;
	j=0;k=1;
    t[k]=s[j];
	tree(0,1);
	tree(1,1);
    //int i;
	//for (i=1;i<=k;i++)
	//	printf("%c %d %d\n",t[i],l[i],r[i]);
	tree_z(1);
	printf("\n");
	tree_h(1);
	printf("\n");
	return 0;
}

C++ :

#include <iostream>
#include <string>
#include <cstdio>
using namespace std;

struct BNode {
	char ch;
	int lchild, rchild;
} node[101];

int root = 0, cnt = 0;

// 创建二叉树 
int buildTree(int T);
// 中序遍历
void inOrder(int T);
// 后序遍历
void postOrder(int T);
int main()
{
	root = buildTree(0);
	inOrder(root);
	cout << endl;
	postOrder(root);
	//cout << root << endl;
	return 0;
}

// 创建二叉树 ABD..EF..G..C..
int buildTree(int T) {
	char ch;
	cin >> ch;
	if (ch == '.') {
		return 0;
	}

	else {
		T = ++cnt;
		node[T].ch = ch;
		node[T].lchild = buildTree(T);
		node[T].rchild = buildTree(T);
	}
	return T;
}

// 中序遍历
void inOrder(int T) {
	if (T) {
		inOrder(node[T].lchild);
		cout << node[T].ch;
		inOrder(node[T].rchild);
	}
}
// 后序遍历
void postOrder(int T) {
	if (T) {
		postOrder(node[T].lchild);
		postOrder(node[T].rchild);
		cout << node[T].ch;
	}
}