玲珑学院 1010 - Alarm

Posted 2020-09-28 十年换你一句好久不见

1010 - Alarm

Time Limit：1s Memory Limit：128MByte

DESCRIPTION

Given a number sequence $[3,7,22,45,116,...]$

. Please tell me the $k$

-th number.

INPUT

A number $\mathrm{T (T<100)}$

$\mathrm{indicates\; the\; number\; of\; the\; input\; cases.\; Then\; for\; each\; case\; there\; only\; is\; one\; integer\; k (1\le k\le 10000)}$

.

OUTPUT

For each case, ouput the $k$

-th number of the sequence in one line.

SAMPLE INPUT

2

1

4

SAMPLE OUTPUT

3

45

第一次做这种题，我的内心是崩溃的找规律找规律  ans=prime(n)^2-n;

来一个数列查找链接 http://oeis.org/

#include <iostream>
#include <cstdio>
#include <cstring>
#include <queue>
#include <cmath>
#include <vector>
#include <algorithm>
using namespace std;
#define lowbit(x) (x&(-x))
#define max(x,y) (x>y?x:y)
#define min(x,y) (x<y?x:y)
#define mem(a) (memset(a,0,sizeof(a)))
typedef long long ll;
ll a[105000];
ll vis[10006];
void getprime()
{
    memset(a,0,sizeof(a));
    a[1]=1;
    for(ll i=2;i<105000;i++)
    {
        if(a[i]==1) continue;
        for(ll j=2;j*i<105000;j++)
            a[j*i]=1;
    }
    ll ans=1;
    for(ll i=2;i<105000;i++)
    {
        if(!a[i]) vis[ans++]=i;
        if(ans>=10002) break;
    }
}
int main()
{
    ll t,n;
    scanf("%lld",&t);
    getprime();
    while(t--)
    {
        scanf("%lld",&n);
        printf("%lld\n", vis[n]*vis[n]-n);
    }
}