count_bottom_leaves.mm

var count_bottom_leaves = function(binary_tree) {
    return helper(binary_tree, get_depth_leaf(binary_tree, 0), 0) 
}

var helper = function(binary_tree, bound_depth, depth) {
    if(binary_tree == false) { return 0 }
    
    var left_node  = get(binary_tree, 1)
    var right_node = get(binary_tree, 2)
    var left_cbl   = 0
    var right_cbl  = 0
    
    if(left_node == false && right_node == false) {
        if(bound_depth == depth + 1) { return 1 }
        else { return 0 }
    }
    else {
        left_cbl  = helper(left_node, bound_depth, depth + 1)
        right_cbl = helper(right_node, bound_depth, depth + 1)
        
        return left_cbl + right_cbl
    }
        
}

var get_depth_leaf = function(binary_tree, depth) {
    if(binary_tree == false) { return depth }
    
    var left_node    = get(binary_tree, 1)
    var right_node   = get(binary_tree, 2)
    var left_depth   = 0
    var right_depth  = 0
    
    
    left_depth  = get_depth_leaf(left_node, depth + 1)
    right_depth = get_depth_leaf(right_node, depth + 1)
    
    if(left_depth > right_depth) { return left_depth }
    else { return right_depth }
    
}

print count_bottom_leaves(array(2, array(5, false, array(7, false, false)), array(9, false, false))) // => 1
print count_bottom_leaves(array(2, array(5, false, array(7, false, false)), array(9, false, array(11, false, false)))) // => 2
print count_bottom_leaves(array(2, array(5, array(6, false, false), array(7, false, false)), array(9, false, array(11, false, false)))) // => 3
print count_bottom_leaves(array(2, array(5, array(6, false, false), array(7, false, false)), array(9, array(10, false, false), array(11, false, false)))) // => 4
print count_bottom_leaves(array(2, array(5, array(6, false, false), array(7, false, false)), array(9, false, false))) // => 2
print count_bottom_leaves(array(2, array(5, array(6, false, array(20, false, false)), array(7, false, false)), array(9, array(10, false, false), array(11, false, false)))) // => 1