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.
class Solution {
public boolean isSubtree(TreeNode s, TreeNode t) {
if(s == null) return false;
if(isSame(s, t)) return true;
return isSubtree(s.left, t) || isSubtree(s.right, t);
}
public boolean isSame(TreeNode s, TreeNode t){
if(s == null || t == null) return s == t;
if(s.val != t.val) return false;
return isSame(s.left,t.left) && isSame(s.right,t.right);
}
}