100. Same Tree(basic Traverse)

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