[force buckle] symmetric binary tree

101. Symmetric binary tree - Power button （LeetCode）

subject ：

Give you the root node of a binary tree  root , Check whether it is axisymmetric .

Ideas ：

Do not look at the root node , Think of a tree as two trees , If it's a symmetric binary tree , The left child of one tree is equal to the right child of another tree

Code ：

bool isSymTree(struct TreeNode* p, struct TreeNode* q){
    if(p==NULL && q==NULL)
    {
        return true;
    }
    if(q==NULL || p == NULL)
    {
        return false;
    }
    if(p->val != q->val)
    {
        return false;
    }

    bool ret1 = isSymTree(p->left,q->right);// Compare p The left subtree of q The right subtree 
    bool ret2 = isSymTree(p->right,q->left);// Compare p Right subtree and q The left subtree 
    
    return ret1 && ret2;
}

bool isSymmetric(struct TreeNode* root){
    if(root == NULL)
    {
        return true;
    }
    return isSymTree(root->left,root->right);// Compare left and right subtrees 
}