对称二叉树（力扣

void inorder(struct TreeNode* q,struct TreeNode*p,int* ret)
{
    if(!q&&!p)
        return;
    else if((!q&&p)||(q&&!p))
    {
        *ret=1;
        return;
    }
    else if(*ret)
        return;
    inorder(q->left,p->right,ret);
    if(q->val!=p->val)
    {
        *ret=1;
        return;
    }
    inorder(q->right,p->left,ret);

}

bool isSymmetric(struct TreeNode* root) {
    int ret=0;
    inorder(root->left,root->right,&ret);
    if(ret)
        return false;
    return true;
}