# PAT 1099. Build A Binary Search Tree (30)

Source: Internet
Author: User

1099. Build A Binary Search Tree (30)

A binary Search Tree (BST) is recursively defined as a Binary Tree which have the following properties:

• The left subtree of a node contains only nodes with keys less than the node ' s key.
• The right subtree of a node contains only nodes with keys greater than or equal to the node ' s key.
• Both the left and right subtrees must also is binary search trees.

Given the structure of a binary tree and a sequence of distinct integer keys, there is only one-through to fill these keys int o The tree so, the resulting tree satisfies the definition of a BST. You is supposed to output the level order traversal sequence of that tree. The sample is illustrated by Figure 1 and 2.

Input Specification:

Each input file contains the one test case. For each case, the first line gives a positive integer N (<=100) which are the total number of nodes in the tree. The next N lines each contains the left and the right children of a node in the format "Left_index Right_index", provided That the nodes was numbered from 0 to N-1, and 0 was always the root. If one child is missing, then-1 would represent the NULL child pointer. Finally N Distinct integer keys is given in the last line.

Output Specification:

For each test case, print in one line the level order traversal sequence of this tree. All the numbers must is separated by a space, with no extra space at the end of the line.

Sample Input:
`91 62 3-1-1-1 45-1-1-17-1-1 8-1-173 45 11 58 82 25 67 38 42`
Sample Output:
`58 25 82 11 38 67 45 73 42`

This problem only needs to know that the pre-sequence of BST to increment sequence can easily set the values of each node

`1#include <iostream>2#include <vector>3#include <algorithm>4#include <queue>5 6 using namespacestd;7 8 structNode9 {Ten     intvalue; One     intleft =-1; A     intright =-1; - }; -  theNode tree[ -]; - intnum[ -]; - intCNT =0; -  + voidPretraversal (intRoot//Use preorder traversal to set the value - { +     if(Root = =-1) A         return; at pretraversal (tree[root].left); -Tree[root].value = num[cnt++]; - pretraversal (tree[root].right); - } -  - voidLeveltraversal (introot) in { -queue<int>que; to Que.push (root); +      while(!que.empty ()) -     { the         intindex =Que.front (); * Que.pop (); \$         if(Index! =root)Panax Notoginsengcout <<" "; -cout <<Tree[index].value; the         if(Tree[index].left! =-1) + Que.push (tree[index].left); A         if(Tree[index].right! =-1) the Que.push (tree[index].right); +     } - } \$  \$ intMain () - { -     intN; theCIN >>N; -      for(inti =0; I < n; i++)WuyiCIN >> Tree[i].left >>Tree[i].right; the      for(inti =0; I < n; i++) -CIN >>Num[i]; WuSort (num, num +n); -  AboutPretraversal (0); \$Leveltraversal (0); -}`

PAT 1099. Build A Binary Search Tree (30)

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