sum of root to path numbers

#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<string,int> psi;
typedef unordered_map<int,int> mii;
typedef unordered_map<long long,long long> mll;
typedef unordered_map<string,int> msi;
typedef unordered_map<char,int> mci;
typedef unordered_set<int> si;
typedef unordered_set<long long> sll;
typedef unordered_set<string> ss;
typedef unordered_set<char> sc;
typedef map<int,int> ormii;
typedef map<long long,long long> ormll;
typedef map<string,int> ormsi;
typedef map<char,int> ormci;
typedef set<int> orsi;
typedef set<long long> orsll;
typedef set<string> orss;
typedef set<char> orsc;
typedef vector<int> vi;
typedef vector<string> vs;
typedef vector<char> vc;
typedef vector<ll> vll;
typedef vector<vector<int>> vvi;
typedef vector<vector<string>> vvs;
typedef vector<vector<ll>> vvll;

#define FOR(i, a, b) for (auto i=a; i<=(b); i++)
#define FORd(i,b,a) for (int i =b; i >= a; i--)
#define sortinc(v)  sort(v.begin(),v.end())
#define sortdec(v)  sort(v.rbegin(),v.rend())
#define sz(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define pob pop_back
#define pf push_front
#define pof pop_front
#define fi first
#define se second
#define ins insert

const int MOD = 1000000007;
//type functions here

class Node
{
    public:
  Node* left;
  Node* right;
    int data;
    Node(int data)
    {
       this->data=data;
        left=NULL;
        right=NULL;
    }
};
int sum;
Node* insert(Node* root,int data)
{
    if(!root) return new Node(data);
    if(data<root->data)
        root->left=insert(root->left,data);
    else
        root->right=insert(root->right,data);
    return root;
}

int digits(int d)
{
    if(d==0) return 1;
    int c=0;
    while(d)
    {
        d/=10;
        c++;
    }
    return c;
}
void print(Node* root,int temp)
{
    if(root==NULL) return;
    int sizee=digits(root->data);

    while(sizee){
    temp=(temp*10)%MOD;
    sizee--;
    }

    temp=(temp+root->data)%MOD;
    if(!root->left&&!root->right)
    {
        sum=(sum+temp)%MOD;
    }
    if(root->left)print(root->left,temp);
    if(root->right)print(root->right,temp);


}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int tc=1;
    cin>>tc;
    FOR(w,1,tc)
    {
       int n;
        cin>>n;
        Node* root=NULL;
        FOR(ww,1,n)
        {
            int temp;
            cin>>temp;
            root=insert(root,temp);
        }
        if(root==NULL) continue;
        sum=0;
        print(root,0);
        cout<<sum<<endl;

    }
    return 0;
}