题解 | #树的子结构#

public class Solution {
    public boolean HasSubtree(TreeNode root1,TreeNode root2) {
        if(root1 ==  null || root2 == null) return false;
        if(dfs(root1,root2)) return true;
        return HasSubtree(root1.left,root2) || HasSubtree(root1.right,root2);
    }
    
    public boolean dfs(TreeNode root1, TreeNode root2) {
        if(root2 == null) return true;
        if(root1 == null && root2 != null) return false;
        return root1.val == root2.val ? dfs(root1.left,root2.left) && 
            dfs(root1.right,root2.right) : false;
    }
}