求二叉树中节点的最大距离

struct node
{
    node *left;
    node *right;
    int maxleft;
    int maxright;
    char value;
};
int max=0;
void findMaxLen(node *root)
{
    if(root==NULL)
        return ;
    if(root->left=NULL)
        root->maxleft=0;
    if(root->right==NULL)
        root->maxright=0;
    if(root->left!=NULL)
        findMaxLen(root->left);
    if(root->right!=NULL)
        findMaxLen(root->right);
    //计算左子树最长节点距离
    if(root->left!=NULL)
    {
        int temp=0;
        if(root->left->maxleft>root->left->maxright)
            temp=root->left->maxleft;
        else
        {
            temp=root->left->maxright;
            
        }
        root->left->maxleft=temp+1;
    }
   //计算右子树最长节点距离
    if(root->right!=NULL)
    {
        int temp=0;
        if(root->right->maxleft>root->right->maxright)
            temp=root->right->maxleft;
        else
        {
            temp=root->right->maxright;
            
        }
        root->right->maxleft=temp+1;
    }
    //更新右子树最长节点的距离
    if(root->maxleft+root->maxright>max)
        max=root->maxleft+root->maxright;
    
}