Leetcode 572. Subtree of Another Tree

1. Description of the topic

You are given two binary trees root and subRoot. Tests that root contains a subtree with the same structure and node values ​​as subRoot. Returns true if present; otherwise, returns false.
A subtree of the binary tree tree includes a certain node of the tree and all descendant nodes of this node. tree can also be seen as a subtree of itself

Example one:

Example two:

2. Link to the original title

Leetcode 572. Subtree of Another Tree

3. Thinking Analysis

Each subtree of root is compared with the tree of SubRoot

Code recursive expansion diagram:

4. Code implementation

bool isSameTree(struct TreeNode* p, struct TreeNode* q)
{
    
    
  //p q 都为空树 
  if( p== NULL && q ==NULL)
  return true ;

  //其中一个为空 
  if(p==NULL || q ==NULL)
     return false ;

     //都不为空 
  if(p->val !=q->val)
  return false ;
    
    //相等
     return isSameTree(p->left , q->left) 
     && isSameTree(p->right , q->right);

}
bool isSubtree(struct TreeNode* root, struct TreeNode* subRoot)
{
    
    
    
    //root为空树 
    if(root ==NULL)
    return false ;
    //root 不为空树 
    if( isSameTree (root ,subRoot))
    return true ;
    //递归 
    return isSubtree(root->left,subRoot) 
    || isSubtree(root->right,subRoot);

}

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