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
题目大意: n(二叉树中结点个数)
假设二叉树中的所有键都是不同的正整数,根据后序遍历和中序遍历求层次遍历
1 #include2 #include 3 #include
解法:1、根据后续遍历和中序遍历转化为前序遍历,并给每个结点赋上index变量:因为后序的最后
一个总是根结点,令i在中序中找到该根结点,则i把中序分为两部分,左边是左子树,右边
是右子树。因为是输出先序(根左右),所以先打印出当前根结点,然后打印左子树,再打
印右子树。左子树在后序中的根结点为root – (end – i + 1),即为当前根结点-(右子树
的个数+1)。左子树在中序中的起始点start为start,末尾end点为i – 1.右子树的根结点
为当前根结点的前一个结点root – 1,右子树的起始点start为i+1,末尾end点为end。
2、根据Map的Key按从小到大排序的特性,使用迭代器把Value值打印出来。