题解 | #求1+2+3+...+n#

class Solution {
public:
class sum
{
    public:
    sum()
    {
        _count += _i;
        ++_i;
    }
};

int Sum_Solution(int n) 
{
    sum arr[n];
    return _count;
}
private:
    static int _i;
    static int _count;
};
int Solution::_i = 1;
int Solution::_count = 0;