Repeating and Missing Python

PROGRAM TO FIND REPEATING AND MISSING NUMBERS

def repeatedNumber(A):

      

    length = len(A)

    Sum_N = (length * (length + 1)) // 2

    Sum_NSq = ((length * (length + 1) * 

                     (2 * length + 1)) // 6)

      

    missingNumber, repeating = 0, 0

      

    for i in range(len(A)):

        Sum_N -= A[i]

        Sum_NSq -= A[i] * A[i]

          

    missingNumber = (Sum_N + Sum_NSq // 

                             Sum_N) // 2

    repeating = missingNumber - Sum_N

      

    ans = []

    ans.append(repeating)

    ans.append(missingNumber)

      

    return ans

  

# Driver code

v = [ 4, 3, 6, 2, 1, 6, 7 ]

res = repeatedNumber(v)

  

for i in res:

    print(i, end = " ")




OUTPUT

6 5 

CREDITS: https://www.geeksforgeeks.org/find-a-repeating-and-a-missing-number/