下面是代码

#include <bits/stdc++.h>
#define int long long
using namespace std;
const int mod =1e9+7;
const int N =100;
int dp[N][N],a[N],ll,rr,pos,tot;
int dfs(int pos, int sum, bool top)
{
        if (!pos) return sum%mod;
        if (!top&&~dp[pos][sum]) return dp[pos][sum]%mod;
        int tmp=top ? a[pos] : 9;
        int ans=0;
        for (int i=0; i<=tmp; i++)
        {
                ans+=dfs(pos-1,sum+i,top&&i==tmp)%mod;
        }
        if (!top) dp[pos][sum]=ans;
        return ans%mod;
}
int solve (int x)
{
        tot=0;
        while (x)
        {
                a[++tot]=x%10;
                x/=10;
        }
        return (dfs(tot,0,1));
}
signed main()
{
        int t;
        cin >> t;
        while (t--)
        {
                memset(dp,-1,sizeof(dp));
                cin >> ll >> rr;
                cout << (solve(rr)-solve(ll-1))%mod << endl;
        }
}