[Li Kou] a subtree of another tree

572. The subtree of another tree - Power button （LeetCode）

subject ：

Here are two binary trees root and subRoot . test root Whether and subRoot Subtrees with the same structure and node values . If there is , return true ; otherwise , return false .

Binary tree tree A subtree of includes tree A node of and all descendants of this node .tree It can also be seen as a subtree of its own .

Ideas ：

Traversal by preorder , When you meet with in the tree subRoot When the value of the hotel is equal , Judge whether it is the same tree , If yes, then subRoot It's a subtree of another tree

Code ：

bool isSameTree(struct TreeNode* root, struct TreeNode* subRoot)
{
    if(root==NULL && subRoot == NULL)
    {
        return true;
    }
    if(root==NULL)
    {
        return false;
    }
    if(subRoot == NULL)
    {
        return false;
    }
    if(root->val != subRoot->val)
    {
        return false;
    }
    bool ret1 = isSameTree(root->left,subRoot->left);
    bool ret2 = isSameTree(root->right,subRoot->right);

    return ret1&&ret2;

}
bool isSubtree(struct TreeNode* root, struct TreeNode* subRoot)
{   
    if(root == NULL && subRoot == NULL)
    {
        return true;
    }
    if(root == NULL)
    {
        return false;
    }
    if(root->val == subRoot->val)// See whether it is the same subtree when the values are equal 
    {
        if(isSameTree(root,subRoot))
        {
            return true;
        }
    }
    bool ret1 = isSubtree(root->left,subRoot);
    bool ret2 = isSubtree(root->right,subRoot);

    return ret1||ret2;

}