Zig Zag Sequence
HackerRank 問題: Zig Zag Sequence
Categories:
Question
In this challenge, the task is to debug the existing code to successfully execute all provided test files.
Given an array of n
distinct integers, transform the array into a zig zag sequence by permuting the array elements. A sequence will be called a zig zag sequence if the first k
elements in the sequence are in increasing order and the last k
elements are in decreasing order, where k = (n+1)/2
. You need to find the lexicographicall
Note: You can modify at most three lines in the given code. You cannot add or remove lines of code.
Answer
def findZigZagSequence(a, n):
a.sort()
# medium calculate fail without -1
mid = int((n + 1)/2) - 1
a[mid], a[n-1] = a[n-1], a[mid]
st = mid + 1
# end index offset wrong at first time
ed = n - 2
while(st <= ed):
a[st], a[ed] = a[ed], a[st]
st = st + 1
# end index should be minus not plus
ed = ed - 1
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)