根据二叉树的先序遍历和中序遍历重构二叉树

/*
 * test.cpp
 *
 *  Created on: Dec 13, 2010
 *      Author: alfred
 */
#include <iostream>
#include <string>
using namespace std;
struct node {
	char data;
	node* left;
	node* right;
	node(char data = '/0', node* left = NULL, node* right = NULL) {
		this->data = data;
		this->left = left;
		this->right = right;
	}
};
void build_left(int, int, node*);
void build_right(int, int, node*);
int cur;
string pre_tra, inorder_tra;
int main() {
	node root;
	while(cin >> pre_tra >> inorder_tra) {
		root.data = pre_tra[0];
		cur = 1;
		int pos = inorder_tra.find(pre_tra[0]);
		build_left(0, pos - 1, &root);
		build_right(pos + 1, inorder_tra.size(), &root);
		post_tra(&root);
	}
	return 0;
}
void build_left(int beg, int end, node* parent) {
	if(beg > end || cur >= pre_tra.size())
		return;
	parent->left = new node(pre_tra[cur]);
	int pos = inorder_tra.find(pre_tra[cur]);
	cur++;
	build_left(beg, pos - 1, &(*parent->left));
	build_right(pos + 1, end, &(*parent->left));
}
void build_right(int beg, int end, node* parent) {
	if(beg > end || cur >= pre_tra.size())
		return;
	parent->right = new node(pre_tra[cur]);
	int pos = inorder_tra.find(pre_tra[cur]);
	cur++;
	build_left(beg, pos- 1, &(*parent->right));
	build_right(pos + 1, end, &(*parent->right));
}