longest increasing in binary tree

longest consective increasing sequence in binary tree.(start point happen anywhere in the node, not necessary start from root)

一亩三分地

没有OJ，继续不知道这样做对不对 分情况讨论

• 左结点，右节点都要返回其递增数目和递减数目
• root节点需要根据左右节点实际值判断是否用递增递减数目
• 考虑到NULL的情况

int getLongest(TreeNode *root)
{
    int up=0,down=0;

    get(root,up,down);

    return maxNum;
}

int maxNum=0;

void get(TreeNode *root,int &up,int &down)
{
    if(root==0)
    {
        up=0,down=0;
    }

    int lup=0,ldown=0;
    int rup=0,rdown=0;

    if(root->left)
    get(root->left,lup,ldown);

    if(root->right)
    get(root->right,rup,rdown);

    if(root->left==NULL)
    {
        if(root->right==NULL)return ;

        if(root->right->val<root->val)down=rdown+1;

        if(root->right->val>root->val)up=rup+1;

        maxNum=max(maxNum,max(down,up));
    }
    else if(root->right==NULL)
    {
        if(root->left->val<root->val)down=ldown+1;

        if(root->left->val>root->val)up=lup+1;

        maxNum=max(maxNum,max(down,up));
    }
    else
    {
        if(root->left->val > root->val && root->val>root->right->val)
        {
            maxNum=max(maxNum,lup+1+rdown);
        }
        else if(root->left->val<root->val && root->val<root->right->val)
        {
            maxNum=max(maxNum,ldown+1+rup);
        }

        if(root->left->val<root->val)
        down=max(down,ldown+1);

        if(root->left->val>root->val)
        up=max(up,lup+1);


        if(root->right->val<root->val)
        down=max(down,rdown+1);

        if(root->right->val>root->val)
        up=max(up,rup+1);
    }
}