Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).
binary tree [1,2,2,3,4,4,3] is symmetric:
1
/ \
2 2
/ \ / \
3 4 4 3[1,2,2,null,3,null,3] is not:
1
/ \
2 2
\ \
3 3Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).
binary tree [1,2,2,3,4,4,3] is symmetric:
1
/ \
2 2
/ \ / \
3 4 4 3[1,2,2,null,3,null,3] is not:
1
/ \
2 2
\ \
3 3