For a binary tree T, we can define a flip operation as follows: choose any node, and swap the left and right child subtrees. A binary tree X is flip equivalent to a binary tree Y if and only if we can make X equal to Y after some number of flip operations. Given the roots of two binary trees root1 and root2, return true if the two trees are flip equivelent or false otherwise. Example 1: Input: root1 = [1,2,3,4,5,6,null,null,null,7,8], root2 = [1,3,2,null,6,4,5,null,null,null,null,8,7] Output: true Explanation: We flipped at nodes with values 1, 3, and 5. Example 2: Input: root1 = [], root2 = [] Output: true Example 3: Input: root1 = [], root2 = [1] Output: false Example 4: Input: root1 = [0,null,1], root2 = [] Output: false Example 5: Input: root1 = [0,null,1], root2 = [0,1] Output: true Constraints: The number of nodes in each tree is in the range [0, 100]. Each tree will have unique node values in the range [0, 99].