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pythonlistdictionaryfor-loopnested-loops

Nested for loop not running in python after the first iteration

I have a nested for loop which is not running after the first iteration

N, M = map(int, input().split())
numbers = map(int, input().split())

dic = {}
for m in range(N):
  dic.setdefault(m,[])
  for n in numbers:
      if n % N == m:
      dic[m].append(n)
print(dic)

The above code is generating the following result {0: [3, 42], 1: [], 2: []} for the sample data down bellow:

3 5
1 3 8 10 42

However I would like to get {0: [3, 42], 1: [1, 10], 2: [8]} What am I doing wrong?

Solution

  • The problem is that map returns an iterator, and you are consuming the iterator completely in the first outer loop. You need:

    numbers = [int(k) for k in input().split()]

    instead of using map.