Basic idea, suppose we have 1,2,3...n, we need to transform it into like this:

1,n,2,n-1,3,n-2,...........

```
class Solution {
public int[] constructArray(int n, int k) {
int[] nums = new int[n];
int count = 1;
int lower = 1;
int higher = n;
int cnt = 0;
while(k--!=0){
if(cnt%2==0){
nums[cnt]=lower;
lower++;
}else{
nums[cnt]=higher;
higher--;
}
cnt++;
}
if(cnt%2==1){
while(cnt<n){
nums[cnt++]=lower++;
}
}else{
while(cnt<n){
nums[cnt++]=higher--;
}
}
return nums;
}
}
```