1452: [蓝桥杯2019初赛]平方和

//1452: [蓝桥杯2019初赛]平方和
#include<iostream>
#include<string>
#include<sstream>
using namespace std;
int main(){
    long long sum = 0;
    int a = 0;
    string::size_type idx;  //string find的返回值 
    string str;
    char c[5];
    for(int i = 1; i <= 2019; i++){
        stringstream ss;
        ss << i;
        string str = ss.str();
        if(str.find('2') != string::npos){  //不等于即说明存在 
            sum += i * i;
        }
        else if(str.find('0') != string::npos){
            sum += i * i;
        }
        else if(str.find('1') != string::npos){
            sum += i * i;
        }
        else if(str.find('9') != string::npos){
            sum += i * i;
        }
    }
    cout<<sum;
    return 0;
}

//1452 方法二：除10判断
#include <iostream>
using namespace std;
long long ans = 0;
bool check(int num){
    bool flag = false;
    while(num){
        int tmp = num % 10;
        if(tmp == 2 || tmp == 0 || tmp == 1 || tmp == 9){
            flag = true;
        }
        num /= 10;
    }
    return flag ? true : false;
}
int main(){
    for(int i=1;i<=2019;i++)
        if(check(i))
            ans+=i*i;
    cout<<ans<<endl;
    return 0;
}