Python:

def findZigZagSequence(a, n):
    a.sort()
    mid = int((n - 1)/2) #first
    a[mid], a[n-1] = a[n-1], a[mid]

    st = mid + 1
    ed = n - 2 #second
    while(st <= ed):
        a[st], a[ed] = a[ed], a[st]
        st = st + 1
        ed = ed - 1 #third

    for i in range (n):
        if i == n-1:
            print(a[i])
        else:
            print(a[i], end = ' ')
    return

test_cases = int(input())
for cs in range (test_cases):
    n = int(input())
    a = list(map(int, input().split()))
    findZigZagSequence(a, n)

hackerrank should fix their stuff, there's no code in c#

am getting same output but it's shows wrong answer why ??

include

include

include

include

int main() {

/* Enter your code here. Read input from STDIN. Print output to STDOUT */    
int temp, mid, l, n, k;
scanf("%d",&l);
scanf("%d",&n);
int a[n];
for(int i=0; i<n; i++){
    scanf("%d",&a[i]);
}
k=(n+1)/2;
for(int i=0; i<n-1; i++){
    for(int j=i+1; j<n; j++)
    {
        if(a[i]>a[j]){
            temp=a[i];
            a[i]=a[j];
            a[j]=temp;
        }
    }
}

int temp1=a[k-1];
    a[k-1]=a[n-1];
    a[n-1]=temp1;
    int j=n-2;
while(k<=j){
    int temp3=a[k];
    a[k]=a[j];
    a[j]=temp3;
    k++;
    j--;
}


for(int i=0;i<n; i++){
    printf("%d",a[i]);
    printf(" ");
}

return 0;

}

The findZigZagSequence function is not provided.

The example provided in description seems misleading, for[2,3,1,5,4]the correct output is [1,2,5,4,3] , however in description we have [1,4,5,3,2] (altough it is mentioned it is a zigzag sequence).

It would be better the descrption updated to say: the correct expected sequence in this case is [1,2,5,4,3]