题解 | #树的子结构#

/**
public class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

    public TreeNode(int val) {
        this.val = val;

    }

}
*/
public class Solution {
    public boolean HasSubtree(TreeNode root1,TreeNode root2) {
         if(root2 == null){
             return false;
         }

        if(root1 == null && root2 != null){
            return false;
        }
        boolean flag = false;
        if(root1.val == root2.val){
            flag = isSubtree(root1, root2);
        }
        if(!flag){
            flag = HasSubtree(root1.left, root2) || HasSubtree(root1.right, root2);
        }
        return flag;
    }

    public boolean isSubtree(TreeNode root1, TreeNode root2){
        if(root2 == null){
            return true;
        }

        if(root1 == null && root2 != null){
            return false;
        }

        if(root1.val == root2.val){
            return isSubtree(root1.left, root2.left) && isSubtree(root1.right, root2.right);
        }else{
            return false;
        }

    }
}