Knows problem naive approach and stack approach.

knows.py

from random import randint

def helloworld():
    matrix = []

    init_data(matrix)
    print_data(matrix)
    #celebrity_index = find_celebrity_naive(matrix)
    celebrity_index = find_celebrity_stack(matrix)
    print("Celebrity that was found :%s" % str(celebrity_index) if celebrity_index!= None else 'None')
    return "Success" if celebrity_index!=None else "Failure!"

def find_celebrity_stack(matrix):
    # push all n elements to the stack , thus pushing 1 to len of matrix to the stack , then check in the matrix if they each other and
    # reach to conclusions
    stack = list(range(0,matrix.__len__()))
    while(stack.__len__() > 1):
        person_1 = stack.pop()
        person_2 = stack.pop()
        # check if person1 knows person2
        if(matrix[person_1][person_2] == 1):
            # if person1 knows person2 , we can discard person1 , else we can discard person2
            stack.append(person_2)
        else:
            stack.append(person_1)
    # now lets check the last person the stack doesnt know anyone
    index_of_the_maybe_celebrity = stack.pop()
    all_zeros = list(filter(lambda x:x == 0 ,matrix[index_of_the_maybe_celebrity]))
    all_ones = []
    for i in range(matrix.__len__()):
        if i!= index_of_the_maybe_celebrity and matrix[i][index_of_the_maybe_celebrity]==1:
            all_ones.append(1)
    if all_zeros.__len__() == matrix.__len__() and all_ones.__len__()==matrix.__len__()-1:
        return index_of_the_maybe_celebrity
    return None

def find_celebrity_naive(matrix):
    # loop through the matrix , find a line with all zeros , and then check if we find 1 collum that has all 1
    for i in range(matrix.__len__()):
        row = matrix[i]
        all_zeros = list(filter(lambda x: x == 0, row))
        if all_zeros.__len__() == row.__len__():
            all_ones = []
            # in case this guys doesnt know anyone , lets check now that everyone knows him , meaning , all cols besides this col
            for j in range(matrix.__len__()):
                if(j!=i and matrix[j][i]==1):
                    all_ones.append(matrix[j][i])
            if all_ones.__len__() == matrix.__len__()-1:
                return i
    return None

def init_data(matrix):
    for i in range(5):
        row = []
        for j in range(5):
            if(i==j):
                row.append(0)
            else:
                row.append(randint(0, 1))
        matrix.append(row)

def print_data(matrix):
    for i in range(matrix.__len__()):
        for j in range(matrix[i].__len__()):
            print(matrix[i][j], end=" ")
        print('\n')


def run_hello_world():
    while helloworld()!="Success":
        helloworld()

run_hello_world()