## Codility : PermMissingElem Python Exercise

A zero-indexed array A consisting of N different integers is given. The array contains integers in the range [1..(N + 1)], which means that exactly one element is missing.

Your goal is to find that missing element.

Write a function:

def solution(A)

that, given a zero-indexed array A, returns the value of the missing element.

For example, given array A such that:

A[0] = 2 A[1] = 3 A[2] = 1 A[3] = 5

the function should return 4, as it is the missing element.

Assume that:

N is an integer within the range [0..100,000];

the elements of A are all distinct;

each element of array A is an integer within the range [1..(N + 1)].

Complexity:

expected worst-case time complexity is O(N);

expected worst-case space complexity is O(1), beyond input storage (not counting the storage required for input arguments).

**Python solution: **

def solution(A):

# write your code in Python 2.7

A=sorted(A)

if not A:

return 1

if 1 not in A:

return 1

if len(A)==1:

return A[0]+1

for i in range(0,len(A)-1):

if (A[i+1]-A[i]) !=1:

return A[i]+1

return A[i+1]+1

You can find python solution on my github account https://github.com/blaz1988/PythonCodility/blob/master/PermMissingElem.py