PAT A1127. ZigZagging on a Tree (30)

Suppose that all the keys in a binary tree are distinct positive integers. A unique binary tree can be determined by a given pair of postorder and inorder traversal sequences. And it is a simple standard routine to PRint the numbers in level-order. However, if you think the problem is too simple, then you are too naive. This time you are supposed to print the numbers in "zigzagging order" -- that is, starting from the root, print the numbers level-by-level, alternating between left to right and right to left. For example, for the following tree you must output: 1 11 5 8 17 12 20 15.

Input Specification:

Each input file contains one test case. For each case, the first line gives a positive integer N (<= 30), the total number of nodes in the binary tree. The second line gives the inorder sequence and the third line gives the postorder sequence. All the numbers in a line are separated by a space.

Output Specification:

For each test case, print the zigzagging sequence of the tree in a line. All the numbers in a line must be separated by exactly one space, and there must be no extra space at the end of the line.

812 11 20 17 1 15 8 512 20 17 11 15 8 5 1Sample Output:
1 11 5 8 17 12 20 15
#include <cstdio>#include<algorithm>#include<queue>#include<vector>using namespace std;const int Max = 40;int n;struct node{	int data,height;	node *lchild,*rchild;};vector<int> S[Max];int post[Max]={0},in[Max]={0};node* BuildTree(int postL,int postR,int inL,int inR,int h){	if(postL>postR)	{		return NULL;	}	node* root = new node;	root->data=post[postR];	root->height=h;	int k;	for(k=inL;k<=inR;k++)	{		if(in[k]==post[postR])		{			break;		}	}	int numL=k-inL;	root->lchild=BuildTree(postL,postL+numL-1,inL,inL+numL-1,h+1);	root->rchild=BuildTree(postL+numL,postR-1,inL+numL+1,inR,h+1);	return root;}int main(){	scanf("%d",&n);	for(int i=0;i<n;i++)	{		scanf("%d",&in[i]);	}	for(int i=0;i<n;i++)	{		scanf("%d",&post[i]);	}	node *root= new node;	root=BuildTree(0,n-1,0,n-1,1);	queue<node*>q;	q.push(root);	int max=0;	while(!q.empty())	{		node* p= new node;		p=q.front();		q.pop();		S[p->height].push_back(p->data);		if(p->height>max) max=p->height;		if(p->lchild!=NULL) q.push(p->lchild);		if(p->rchild!=NULL) q.push(p->rchild);	}    for(int i=1;i<=max;i++)	{		if(i%2==0)		{			for(int j=0;j<S[i].size();j++)			{				printf("%d",S[i][j]);				if(i==max&&j==S[i].size()-1)					printf("/n");				else printf(" ");			}					}		else 		{						for(int j=S[i].size()-1;j>=0;j--)			{				printf("%d",S[i][j]);				if(i==max&&j==0)					printf("/n");				else printf(" ");			}		}	}	system("pause");	return 0;}