Syntax error Program to count elements whose next element also in the array in Python

Program to count elements whose next element also in the array in Python

Suppose we have a list of numbers say nums, we have to find the number of elements x in the array, such that x + 1 also exists in the array.

So, if the input is like nums = [4, 2, 3, 3, 7, 9], then the output will be 3, because 2+1 = 3 is present, 3+1 = 4 is present and another 3 is present so total 3.

To solve this, we will follow these steps −

  • answer := 0

  • c := a list containing frequencies of each elements present in nums

  • dlist := a list from list of all keys of c

  • for each i in dlist, do

    • if c[i + 1] > 0, then

      • answer := answer + c[i]

  • return answer

Example

Let us see the following implementation to get better understanding

from collections import Counter
def solve(nums):
   answer = 0
   c = Counter(nums)
   dlist = list(c.keys())
   for i in dlist:
      if c[i + 1] > 0:
         answer += c[i]

   return answer

nums = [4, 2, 3, 3, 7, 9]
print(solve(nums))

Input

[4, 2, 3, 3, 7, 9]

Output

3
Updated on: 2021-10-11T06:57:47+05:30

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