Array : Finding missing number between from 1 to n

In this article, we delve into the problem of finding the missing number in an integer array containing elements from 1 to n. We present an efficient algorithm in Python to identify the missing number and explain the underlying logic step-by-step. By leveraging the concept of arithmetic progression and using the sum formula, we can quickly locate the missing element in the array. This technique is particularly useful when dealing with datasets where one or more numbers are missing, and it helps ensure data integrity and completeness. Learn how to tackle the missing number problem and gain insights into its applications in data analysis and algorithmic problem-solving.

## code 

def find_missing_numbers(arr):
n = 100  # Highest number in the range
presence = [False] * n  # Array to mark the presence of numbers
# Mark numbers present in the array
for num in arr:
presence[num - 1] = True

missing_numbers = []
# Find missing numbers
for i in range(n):
if not presence[i]:
missing_numbers.append(i + 1)

return missing_numbers

#Array

array = [1, 2, 3, 4, 6, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17, 18, 19, 20,
 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37,
 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54,
 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71,
 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88,
 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100]



missing_numbers = find_missing_numbers(array)
print("Missing Numbers:", missing_numbers)

Output :

Missing Numbers: [5, 12]