Suppose we have an array called nums, this array contains even number of elements, and have another value k. We have to split nums into exactly n/2 pairs such that the sum of each pair is divisible by k. If we can do so then return true, otherwise false.
So, if the input is like nums = [9,5,3,4,7,10,20,8] k = 3, then the output will be True because we can make pairs like (9,3), (5,7), (4,20), (8,10), sum of all pairs are divisible by 3.
To solve this, we will follow these steps −
dp := a new list
count:= 0
for each x in nums, do
t:= k - (x mod k)
if t is same as k, then
count := count + 1
otherwise,
insert t at the end of dp
if count mod 2 is not same as 0, then
return False
sort the list dp
low := 0
high := size of dp - 1
while low < high, do
if dp[low] + dp[high] is not same as k, then
return False
low := low + 1
high := high - 1
return True
Let us see the following implementation to get better understanding −
Example
def solve(nums, k): dp=[] count=0 for x in nums: t=k-(x % k) if t == k: count+=1 else: dp.append(t) if count % 2 != 0: return False dp.sort() low = 0 high = len(dp)-1 while low < high: if dp[low] + dp[high] != k: return False low += 1 high -= 1 return True nums = [9,5,3,4,7,10,20,8] k = 3 print(solve(nums, k))
Input
[9,5,3,4,7,10,20,8], 3
Output
True