Suppose that all the keys in a binary tree are distinct positive integers. Given the postorder and inorder traversal sequences, you are supposed to output the level order traversal sequence of the corresponding binary tree.
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 postorder sequence and the third line gives the inorder sequence. All the numbers in a line are separated by a space.
Output Specification:
For each test case, print in one line the level order traversal sequence of the corresponding binary tree. 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.
Sample Input:
7 2 3 1 5 7 6 4 1 2 3 4 5 6 7
Sample Output:
4 1 6 3 5 7 2
1 #include <stdio.h>
2 #include <stdlib.h>
3 #include <iostream>
4 #include <string.h>
5 #include <math.h>
6 #include <algorithm>
7 #include <string>
8 #include <stack>
9 #include <queue>
10 using namespace std;
11 struct node{
12 int data;
13 node * left;
14 node *right;
15 };
16 const int maxn=50;
17 int in[maxn];
18 int post[maxn];
19 node * create(int a,int b,int c,int d)
20 {
21 if(a>b)return NULL;
22 node * newnode=new node;
23 newnode->data=post[b];
24 //后序最后一个节点
25 int k=0;
26 for(;k+c<=d;k++)
27 {
28 if(in[k+c]==post[b])
29 {
30 break;
31 }
32 }
33 newnode->left=create(a,a+k-1,c,c+k-1);
34 newnode->right=create(a+k,b-1,c+k+1,d);
35 return newnode;
36 }
37 int n;
38 int BFS(node * root )
39 {
40 queue<node *> q;
41 int num=0;
42 q.push(root);
43 while(!q.empty())
44 {
45 node * temp=q.front();
46 q.pop();
47 printf("%d",temp->data);
48 num++;
49 if(num<n)printf(" ");
50 if(temp->left!=NULL)q.push(temp->left);
51 if(temp->right!=NULL)q.push(temp->right);
52 }
53 }
54
55 int main(){
56
57 scanf("%d",&n);
58
59 for(int i=0;i<n;i++)
60 {
61 scanf("%d",&post[i]);
62 }
63 for(int i=0;i<n;i++)
64 {
65 scanf("%d",&in[i]);
66 }
67
68 node * root=create(0,n-1,0,n-1);
69 BFS(root);
70 return 0;
71 }