| B | 随机序列 |
题意：算方差和极差，超简单
ac代码：
#include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;
#define ll long long
#define N 10004
int main()
{
int t;
cin>>t;
while(t--){
ll max1=-111,min1=60000;
int n;
cin>>n;
ll a[N];
double sum=0,sum1=0;
for(int i=0;i<n;i++){
cin>>a[i];
sum+=a[i];
max1=max(max1,a[i]);
min1=min(min1,a[i]);
}
sum=sum*1.0/n;
for(int i=0;i<n;i++){
sum1+=(a[i]-sum)*(a[i]-sum);
}
cout<<max1-min1<<" ";
printf("%.3lf\n",sum1/n);
}
}
| D |
本题最简单，相信都会
#include<iostream>
using namespace std;
int main()
{
int a;
cin>>a;
if(a%2==0)
cout<<a/2<<endl;
else cout<<3*a+1<<endl;
}