统计数字2出现的次数 - C++代码实现

#include using namespace std;

int count2(int n) { int count = 0; while (n > 0) { if (n % 10 == 2) { count++; } n /= 10; } return count; }

int main() { int L, R; cin >> L >> R;

int count = 0;
for (int i = L; i <= R; i++) {
    count += count2(i);
}

cout << count << endl;

return 0;

}