codeforces C. Mashmokh and Numbers

题意：给你n和k，然后让你找出n个数使得gcd（a1,a2）+gcd(a3,a4)+......的和等于k；

思路：如果n为奇数，让前n-3个数的相邻两个数都为1，n-2和n-1两个数gcd为k-ans；ans为前n-3个数的和。为偶数的话，让前n-2个数的相邻两个数都为1，n和n-1两个数gcd为k-ans；

#include <cstdio>
#include <cmath>
#include <cstring>
#include <vector>
#include <algorithm>
#define maxn 10000
#define ll long long
using namespace std;


int n,k;
vector<int>q;

int main()
{
    scanf("%d%d",&n,&k);
    if((n%2==0&&(n/2)>k)||(n%2!=0&&(n-1)/2>k))
    {
        printf("-1
");
    }
    else
    {
        if(n==1&&k==0)
        {
            printf("1
");
            return 0;
        }
        else if(n==1&&k>0)
        {
            printf("-1
");
            return 0;
        }
        if(n%2==0)
        {
            int ans=0;
            ll c=1000000000;
            for(int i=1; i<=n-2; i+=2)
            {
                printf("%lld %lld ",c,c-1);
                c-=2;
                ans++;
            }
            printf("%lld %lld
",(ll)(k-ans),(ll)((k-ans)*2));
        }
        else
        {
            int ans1=0;
            ll c1=1000000000;
            for(int i=1; i<n-2; i+=2)
            {
                printf("%lld %lld ",c1,c1-1);
                c1-=2;
                ans1++;
            }
            printf("%lld %lld",(ll)(k-ans1),(ll)(k-ans1)*2);
            printf(" %lld
",c1);
        }
    }
    return 0;
}