1700.NumberofStudentsUnabletoEatLunch.py

'''
    The school cafeteria offers circular and square sandwiches 
    at lunch break, referred to by numbers 0 and 1 respectively. 
    All students stand in a queue. Each student either prefers 
    square or circular sandwiches.

    The number of sandwiches in the cafeteria is equal to the 
    number of students. The sandwiches are placed in a stack. 
    At each step:
        - If the student at the front of the queue prefers 
          the sandwich on the top of the stack, they will 
          take it and leave the queue.
        - Otherwise, they will leave it and go to the queue's 
          end.

    This continues until none of the queue students want to 
    take the top sandwich and are thus unable to eat.

    You are given two integer arrays students and sandwiches 
    where sandwiches[i] is the type of the i​​​​​​th sandwich in 
    the stack (i = 0 is the top of the stack) and students[j] 
    is the preference of the j​​​​​​th student in the initial queue 
    (j = 0 is the front of the queue). Return the number of 
    students that are unable to eat.

    Example:
    Input: students = [1,1,0,0], sandwiches = [0,1,0,1]
    Output: 0 
    Explanation:
                - Front student leaves the top sandwich and 
                  returns to the end of the line making 
                  students = [1,0,0,1].
                - Front student leaves the top sandwich and 
                  returns to the end of the line making 
                  students = [0,0,1,1].
                - Front student takes the top sandwich and 
                  leaves the line making students = [0,1,1] 
                  and sandwiches = [1,0,1].
                - Front student leaves the top sandwich and 
                  eturns to the end of the line making 
                  students = [1,1,0].
                - Front student takes the top sandwich and 
                  leaves the line making students = [1,0] 
                  and sandwiches = [0,1].
                - Front student leaves the top sandwich and 
                  returns to the end of the line making 
                  students = [0,1].
                - Front student takes the top sandwich and 
                  leaves the line making students = [1] and 
                  sandwiches = [1].
                - Front student takes the top sandwich and 
                  leaves the line making students = [] and 
                  sandwiches = [].
                Hence all students are able to eat.

    Example:
    Input: students = [1,1,1,0,0,1], sandwiches = [1,0,0,0,1,1]
    Output: 3

    Constraints:
        - 1 <= students.length, sandwiches.length <= 100
        - students.length == sandwiches.length
        - sandwiches[i] is 0 or 1.
        - students[i] is 0 or 1.
'''
#Difficulty: Easy
#55 / 55 test cases passed.
#Runtime: 36 ms
#Memory Usage: 14.4 MB

#Runtime: 36 ms, faster than 84.36% of Python3 online submissions for Number of Students Unable to Eat Lunch.
#Memory Usage: 14.4 MB, less than 23.56% of Python3 online submissions for Number of Students Unable to Eat Lunch.

class Solution:
    def countStudents(self, students: List[int], sandwiches: List[int]) -> int:
        stuck_in_queue = 0
        while stuck_in_queue < len(students):
            student = students.pop(0)
            if sandwiches[0] == student:
                sandwiches.pop(0)
                stuck_in_queue = 0
            else:
                students.append(student)
                stuck_in_queue += 1
        return stuck_in_queue