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### by Sumit Chourasia | Oct 07, 2020 | Category :coding | Tags : algorithmbinary-treedata-structureeasyleetcodetree #### Subtree of Another Tree - Tree - Easy - LeetCode

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.

``````/**
* Definition for a binary tree node.
* public class TreeNode {
*     public int val;
*     public TreeNode left;
*     public TreeNode right;
*     public TreeNode(int val=0, TreeNode left=null, TreeNode right=null) {
*         this.val = val;
*         this.left = left;
*         this.right = right;
*     }
* }
*/
public class Solution {
public bool IsSubtree(TreeNode s, TreeNode t) {
if(t==null){
return true;
}
if(s==null && t!=null){
return false;
}

if(s.val==t.val){
if(IsEqual(s.left,t.left) && IsEqual(s.right,t.right)){
return true;
}
}

return IsSubtree(s.left,t) || IsSubtree(s.right,t);
}

private bool IsEqual(TreeNode s, TreeNode t){
if(s==null && t == null){
return true;
}

if(s==null || t == null){
return false;
}

if(s.val != t.val){
return false;
}

return IsEqual(s.left,t.left) && IsEqual(s.right,t.right);
}
}``````

Time Complexity: O(2^n)

Space Complexity: O(1)