蓝桥杯--门牌制作

https://www.lanqiao.cn/problems/592/learning/

#include<cstdio>
int main(){
    int a,i=0,ans=0;
    for(i=1;i<=2020;i++){
        if(i%10==2)ans++;
        if(i/10%10==2)ans++;
        if(i/100%10==2)ans++;
        if(i/1000%10==2)ans++;
    }
    printf("%d",ans);
    
}