p1179数字统计

#include<iostream>typedef long long ll;using namespace std;int fun(ll x){ll c=0;while(x){if(x%10==2)c++;x/=10;}return c;}int main(){ll l,r;int sum;cin>>l>>r;for(ll i=l;i<=r;i++)sum+=fun(i);//  数字方法统计存在2的个数cout<<sum<<endl;return 0;}