Your test case is invalid


#1

67 0 4 4 10 6 6 10 16 3 14 9 9 14 3 16 13 -1 7 11 -1 -1 -1 15 15 -1 -1 -1 11 7 -1 13 -1 12 -1 1 -1 -1 -1 -1 -1 -1 -1 -1 1 -1 12 -1 8 -1 5 2 2 5 -1 8 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1

This is NOT a symmetric tree.


                        67
                        / \
                       /   \
                      /     \
                     /       \
                    /         \
                   /           \
                  /             \
                 /               \
                /                 \
               0                   4
              / \                 / \
             /   \               /   \
            /     \             /     \
           /       \           /       \
          /         \         6         6
         4          10       / \       / \
        / \         / \     9   9     /   \
       /   \       3  14   / \       /     \
      /     \     /       /   \     /       \
     10     16   11      15   15   14        3
    / \       \                     \       /
   /   \       7                    11     7
  16   13     /                       \     \
 /     /     1                         1    12
13    12    / \                       /     /
 \     \   2   2                     5     8
  8     5


#2

67 is the number of nodes and not a node itself.