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  • 递归与二叉树_中序和后序重建二叉树

    # coding: utf-8
    '''
    题目:输入某二叉树的前序遍历和中序遍历的结果,请重建出该二叉树。
    假设输入的前序遍历和中序遍历的结果中都不含重复的数字。
    '''
    class Node:
    def __init__(self, data, left, right):
    self.data = data
    self.left = left
    self.right = right


    def construct_tree(pre_order, mid_order):
    # 忽略参数合法性判断
    if len(pre_order) == 0 :
    return None
    # 前序遍历的第一个结点一定是根结点
    root_data = pre_order[0]
    for i in range(0, len(mid_order)):
    if mid_order[i] == root_data:
    break
    # 递归构造左子树和右子树
    left = construct_tree(pre_order[1 : 1 + i], mid_order[:i])
    right = construct_tree(pre_order[1 + i:], mid_order[i+1:])

    return Node(root_data, left, right)


    if __name__ == '__main__':
    pre_order = [1, 2, 4, 7, 3, 5, 6, 8]
    mid_order = [4, 7, 2, 1, 5, 3, 8, 6]
    root = construct_tree(pre_order, mid_order)
    print root.data
    print root.left.data
    print root.right.data
    print root.left.left.data
    print root.left.left.right.data
    print root.right.right.left
    print root.right.left.data
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  • 原文地址:https://www.cnblogs.com/lux-ace/p/10546829.html
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