Given two binary trees, write a function to check if they are equal or not. Two binary trees are considered equal if they are structurally identical and the nodes have the same value.
1 public boolean isSameTree(TreeNode p, TreeNode q) { 2 if(p == null && q == null) return true; 3 if(p == null || q == null) return false; 4 if(p.val == q.val) 5 return isSameTree(p.left, q.left) && isSameTree(p.right, q.right); 6 return false; 7 }