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.

2.symmetric tree

Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).

For example, this binary tree is symmetric:

    1/ \2   2/ \ / \
3  4 4  3

But the following is not:

    1/ \2   2\   \3    3

Note:
Bonus points if you could solve it both recursively and iteratively.

/*** Definition for binary tree* public class TreeNode {*     int val;*     TreeNode left;*     TreeNode right;*     TreeNode(int x) { val = x; }* }*/
public class Solution {public boolean isSameTree(TreeNode p, TreeNode q) {if(p==null && q==null) return true;if(p==null || q==null || q.val!=p.val ) return false;if(isSameTree(p.left,q.left)==false || isSameTree(p.right,q.right)==false) return false;return true;}
}

/*** Definition for binary tree* public class TreeNode {*     int val;*     TreeNode left;*     TreeNode right;*     TreeNode(int x) { val = x; }* }*/
public class Solution {public boolean isSymmetric(TreeNode root) {if (root==null) return true;return isEquel(root.left,root.right);}public boolean isEquel(TreeNode root1,TreeNode root2){if(root1==null && root2==null) return true; if(root1==null || root2==null) return false;if(root1.val!=root2.val) return false;return isEquel(root1.left,root2.right) && isEquel(root2.left,root1.right); }
}