617. Merge Two Binary Trees

最新推荐文章于 2025-12-09 19:50:25 发布

原创最新推荐文章于 2025-12-09 19:50:25 发布 · 313 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#C++ #算法

Homework 专栏收录该内容

11 篇文章

订阅专栏

本文介绍了一种将两棵二叉树合并为一棵新二叉树的算法。当两棵树的节点重叠时，新树的节点值为两节点值之和；若不重叠，则采用非空节点值。该算法从根节点开始递归处理。

Given two binary trees and imagine that when you put one of them to cover the other, some nodes of the two trees are overlapped while the others are not.

You need to merge them into a new binary tree. The merge rule is that if two nodes overlap, then sum node values up as the new value of the merged node. Otherwise, the NOT null node will be used as the node of new tree.

Example 1:

Input: 
	Tree 1                     Tree 2                  
          1                         2                             
         / \                       / \                            
        3   2                     1   3                        
       /                           \   \                      
      5                             4   7                  
Output: 
Merged tree:
	     3
	    / \
	   4   5
	  / \   \ 
	 5   4   7

Note:The merging process must start from the root nodes of both trees.

解题思路：先判定两棵树的相同位置是否为空，都不为空时才进行运算。

if （t1 == nil && t2 == nil）{

        return nil；
    }
    if（t1 != nil && t2 == nil）{
        return t1；
    }
    if（t1 == nil && t2 != nil）{
        return t2；
    }
    if（t1 != nil && t2 != nil）{
        t1.Val += t2.Val；
        t1.Left = mergeTrees(t1.Left, t2.Left);
        t1.Right = mergeTrees(t1.Right, t2.Right);
    }
    return t1;