#include <bits/stdc++.h>
using namespace std;
int main()
{
	int a, b, c;
    cin >> a >> b >> c;
    cout << (a * 2 + b * 3 + c * 5) / 10;
	return 0;
}

#include<bits/stdc++.h>
using namespace std;
int main()
{
    double a, b, c;
    cin >> a >> b >> c;
    a = a * 0.2 +b * 0.3 + c * 0.5;
    cout << a ;
    return 0;
}

A

#include <bits/stdc++.h>
using namespace std;
double a, b, c;
int main()
{
    cin >> a >> b >> c;
    cout << a * 0.2 + b * 0.3 + c * 0.5;
    return 0;
}

#include <bits/stdc++.h>
using namespace std;
int main()
{
    double a, b, c;
    cin >> a >> b >> c;
    cout << a * 0.20 + b * 0.30 + c * 0.50;
    return 0;
}

#include <cstdio>
using namespace std;
int main()
{
    int a, b, c;
    scanf("%d%d%d", &a, &b, &c);
    int sum = a * 0.2 + b * 0.3 + c * 0.5;
    printf("%d\n", sum);
    return 0;
}

全场最简：

#include <bits/stdc++.h>
int a , b , c;
int main()
{
    std::cin >> a >> b >> c;
    std::cout << a * 0.2 + b * 0.3 + c * 0.5;
    return 0;
}

《“极简”版》

#include <bits/stdc++.h>//好习惯
using namespace std;
int main()
{
double a, b, c;
cin >> a >> b >> c;
double aa = a * 0.2;
double bb = b * 0.3;
double cc = c * 0.5;
int s = aa + bb + cc;
cout << s;
return 0;//又一个好习惯
}

已AC😄