617. Merge Two Binary Trees

最新推荐文章于 2023-11-12 11:08:54 发布

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本文介绍了一种将两棵可能部分节点重叠的二叉树合并的方法。合并时，如果两个树的节点重叠，则它们的值相加作为新节点的值；如果不重叠，则保留非空节点。提供了一个具体的例子并附带了实现该功能的C++代码。

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.

class Solution {
public:
    TreeNode* mergeTrees(TreeNode* t1, TreeNode* t2) {
        if (!t1 && !t2) return nullptr;

        TreeNode* node = new TreeNode((t1 ? t1->val : 0) + (t2 ? t2->val : 0));
        node->left = mergeTrees((t1 ? t1->left : nullptr), (t2 ? t2->left : nullptr));
        node->right = mergeTrees((t1 ? t1->right : nullptr), (t2 ? t2->right : nullptr));
        return node;
    }
};