2999 - 求1+3+5+……+n

5

s=9

Solution C++

#include<bits/stdc++.h>
using namespace std;
int n,s;
int main()
{
	cin>>n;
	for(int i=1;i<=n;i+=2)
		s+=i;
	cout<<"s="<<s;	
	return 0;
}