Python Solution

[daxiong930]

def find_min(x):
    while x.left != None:
        x = x.left
    else:
        return x.val
    
def find_max(x):
    while x.right != None:
        x = x.right
    else:
        return x.val

def myGetMinimumDifference(root):
    min_value = float('inf')
    if root.left == None and root.right == None:
        return float('inf')
    
    if root.right != None:
        min_value = abs(root.val-find_min(root.right))
        min_value = min(min_value,myGetMinimumDifference(root.right))
    if root.left != None:
        min_value = min(min_value,abs(find_max(root.left) - root.val))
        min_value = min(min_value,myGetMinimumDifference(root.left))
    return min_value