2101 Problem A Snake Filled

“What a boring world!”
Julyed felt so bored that she began to write numbers on the coordinate paper. She wrote a “0” on the center, then wrote the follow numbers clockwise, which looked like a snake as below.
“Damn! I have fulfilled the paper!”
Julyed was looking at paper. Suddenly, she began to feel curious.
“What is the nth number on the positive axis of Y axis?”
She asked tomriddly for the question. But tomriddly was so busy that he ignored Julyed. So now you have to solve this problem.

Multiple test cases.
The first line contains an integer T (T <= 50), indicating the number of test cases.
Then T lines follows, one line per case. Each line contains a positive integer n (n <= 3000).

One line per case. An integer indicates the nth number on the positive axis of Y axis.

3
1
2
18

5
18
1314

解题心得：
　　输入0，1,2...，然后对应输出黄色标记的数字。此题纯靠找规律即可解答。
　　我找到的规律是这样的：0,5,18,39 ，每次增加的数add[1]=4,add[2]=13,add[3]=21，然后发现每个add之间都是增加8；
　　下面是代码。

代码：

#include <iostream>
#include <cstdio>
#include <cstring>

using namespace std;

int main()
{
    int n;
    int add=5;
    int a[3005];
    int z=8;
    int s=0;
    int ii;
    memset(a,0,3005*sizeof(int));
    cin>>n;
    for(int i=0;i<n;i++){
        for(int j=1;j<=3000;j++){
            s+=add;
            a[j]=s;
            add+=z;
        }
        s=0;
        add=5;
        scanf("%d",&ii);
        printf("%d\n",a[ii]);
    }
    return 0;
}