BOJ11170 : 0의 개수 (Silver 5)

#include <iostream>
#include <string>

using namespace std;
int number(int a)
{
    int count = 0;
    string str = to_string(a);
    for (int i = 0; i < str.length(); i++)
    {
        if (str[i] == '0')
        {
            count++;
        }
    }
    return count;
}

int main()
{
    int T, N, M;
    cin >> T;
    for (int i = 0; i < T; i++)
    {
        cin >> N >> M;
        int count = 0;
        for (int j = N; j <= M; j++)
        {
            count += number(j);
        }
        cout << count <<"\n";
    }
}