Counting Invisible Nodes of Binary Tree.

gistfile1.java

class Solution {
    
    int total_nodes = 0;
    int nonvisible_nodes = 0;
    
    public int solution(Tree T) {
        traverse(T, Integer.MIN_VALUE);
        return total_nodes - nonvisible_nodes;
    }
    
    public void traverse(Tree T, int cur_max) 
    {
        if(T != null) 
            total_nodes++;
        else
            return;

      if(T.x > cur_max) 
            cur_max = T.x;

        if(T.x < cur_max) 
            nonvisible_nodes++;
        
        traverse(T.l, cur_max);
        traverse(T.r, cur_max);
    }
}