题解 | #求1+2+3+...+n#
求1+2+3+...+n
https://www.nowcoder.com/practice/7a0da8fc483247ff8800059e12d7caf1
class Solution {
public:
int Sum_Solution(int n) {
// ret = n^2/2 + n / 2;
double ret = pow(n, 2) + n;
return (int) ret / 2;
}
};
