"""
A non-empty array A consisting of N integers is given.
A permutation is a sequence containing each element from 1 to N once, and only once.
For example, array A such that:
    A[0] = 4
    A[1] = 1
    A[2] = 3
    A[3] = 2 
is a permutation, but array A such that:
    A[0] = 4
    A[1] = 1
    A[2] = 3 
is not a permutation, because value 2 is missing.
The goal is to check whether array A is a permutation.
Write a function:
def solution(A)
that, given an array A, returns 1 if array A is a permutation and 0 if it is not.
For example, given array A such that:
    A[0] = 4
    A[1] = 1
    A[2] = 3
    A[3] = 2 
the function should return 1.

Given array A such that:
    A[0] = 4
    A[1] = 1
    A[2] = 3 
the function should return 0.
Write an efficient algorithm for the following assumptions:
N is an integer within the range [1..100,000];
each element of array A is an integer within the range [1..1,000,000,000].

"""


def Solution(A):
    ideal_list = list(range(1, len(A) + 1))
    return int(sum(A) == sum(ideal_list) and len(set(A)) == len(ideal_list))
