（算法练习）蓝桥杯——小明对数位中含有 2、0、1、9 的数字很感兴趣

要求：
https://www.dotcpp.com/oj/contest2325_problem16.html

感觉蓝桥杯的代码比较难AC，处处有坑= =
不过这一题算比较简单了~
AC代码：

#include <stdio.h>
#include <string>
#include <iostream>
#include <sstream>
using namespace std;

int F(int n,int sum){
    
    
	stringstream ss;
	ss<<n;
	string str;
	ss>>str;
	
	for(int i = 0;i <str.size();i++){
    
    
		if(str[i] -'0' == 2 || str[i] -'0' == 0 || str[i] -'0' == 1 || str[i] -'0' == 9 ){
    
    
			sum = sum + n;
			//printf("sum=%d\n",sum);
			break;
		}
	}
	return sum;
	
}


int main(){
    
    
	int n;
	scanf("%d",&n);
	int sum = 0;
	int cnt = 0;
	for(int i = 1;i <= n;i++){
    
    
		cnt = cnt + F(i,sum);
	}
	printf("%d",cnt);
	
}