Given two non-empty binary trees s and t, check whether tree t has exactly the same structure and node values with a subtree of s. A subtree of s is a tree consists of a node in s and all of this node's descendants. The tree s could also be considered as a subtree of itself.

Example 1: Given tree s:

       3    

      / \   

    4   5  

   / \

 1   2

Given tree t:   

   4  

  / \

 1   2

Return true, because t has the same structure and node values with a subtree of s.

Example 2: Given tree s:

       3   

      / \   

    4   5  

    / \

   1   2   

        /   

      0

Given tree t:   

    4  

   / \

 1   2

Return false.