Program to find a sub-list of size at least 2 whose sum is multiple of k in Python

Suppose we have a list of non-negative numbers called nums and another positive value k. We have to find check whether there is any sublist of length at least 2 whose sum is multiple of k or not.

So, if the input is like nums = [12, 6, 3, 4] k = 5, then the output will be True, as the sublist is [12, 3] sums to 15 which is divisible by 5.

To solve this, we will follow these steps −

• sum := 0
• m := a new map
• m[0] := -1
• for i in range 0 to size of nums, do
  • sum := sum + nums[i]
  • sum := sum mod k
  • if sum is present in m, then
    • if i - m[sum] >= 2, then
      • return True
  • otherwise,
    • m[sum] := i
• return False

Let us see the following implementation to get better understanding −

Example

 Live Demo

class Solution:
   def solve(self, nums, k):
      sum = 0
      m = {}
      m[0] = -1
      for i in range(0, len(nums)):
         sum += nums[i]
         sum %= k
         if sum in m:
            if i - m[sum] >= 2:
               return True
         else:
            m[sum] = i
      return False
ob = Solution()
nums = [12, 6, 3, 4]
k = 5
print(ob.solve(nums, k))

Input

[12, 6, 3, 4], 5

Output

True

Arnab Chakraborty

Updated on: 19-Nov-2020

96 Views

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