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.
题目含义：判断一个树是否是另外一个树的子结构
1 private boolean isSame(TreeNode s, TreeNode t) { 2 if (s == null && t == null) return true; 3 if (s == null || t == null) return false; 4 5 if (s.val != t.val) return false; 6 7 return isSame(s.left, t.left) && isSame(s.right, t.right); 8 } 9 10 public boolean isSubtree(TreeNode s, TreeNode t) { 11 if (s ==null) return false; 12 if (isSame(s,t)) return true; 13 return isSubtree(s.left,t) || isSubtree(s.right,t); 14 }