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.

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