100.Same Tree

Solution 1 : inorder(ON)

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