Find missing element in a sorted array of consecutive numbers in Python
Suppose we have an array A of n unique numbers, these n elements are present in the array in ascending order, but there is one missing element. We have to find the missing element.
So, if the input is like A = [1, 2, 3, 4, 5, 6, 7, 9], then the output will be 8.
To solve this, we will follow these steps −
n := size of A
left := 0
right := n - 1
mid := 0
while right > left , do
return -1
Example
Let us see the following implementation to get better understanding −
Live Demo
def search_missing_item(A):
n = len(A)
left, right = 0, n - 1
mid = 0
while (right > left):
mid = left + (right - left) // 2
if (A[mid] - mid == A[0]):
if (A[mid + 1] - A[mid] > 1):
return A[mid] + 1
else:
left = mid + 1
else:
if (A[mid] - A[mid - 1] > 1):
return A[mid] - 1
else:
right = mid - 1
return -1
A = [1, 2, 3, 4, 5, 6, 7, 9]
print(search_missing_item(A))
Input
[1, 2, 3, 4, 5, 6, 7, 9]
Output
8
Published on 25-Aug-2020 15:07:46
