floorInBST

#include <bits/stdc++.h> 
/************************************************************

    Following is the TreeNode class structure

    template <typename T>
    class TreeNode {
       public:
        T val;
        TreeNode<T> *left;
        TreeNode<T> *right;

        TreeNode(T val) {
            this->val = val;
            left = NULL;
            right = NULL;
        }
    };

************************************************************/

int solve(TreeNode<int> * root, int X , int* mx)
{
    if(root == NULL){
        return -1;
    }
    if(root->val > X){
        return solve(root->left , X , mx);
    }
    else if(root->val < X){
        *mx = max(*mx , root->val);
        return solve(root->right ,X , mx);
    }
    else{
        *mx = max(*mx , root->val); 
        return *mx;
    }
}

int floorInBST(TreeNode<int> * root, int X)
{
    int ans = -1;
    solve(root , X , &ans);
    return ans;
}