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.
public class Solution { public boolean isSameTree(TreeNode p, TreeNode q) { if(p== null && q ==null)return true; if(p == null || q == null) return false; if(p.val != q.val) return false; return isSameTree(p.left,q.left)&& isSameTree(p.right,q.right); } }