Number of Students Unable to Eat Lunch — LeetCode 1700 Python Solution

The problem

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.

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].

Python solution

class Solution:
    def countStudents(self, students: List[int], sandwiches: List[int]) -> int:
        cnt = Counter(students)
        for v in sandwiches:
            if cnt[v] == 0:
                return cnt[v ^ 1]
            cnt[v] -= 1
        return 0

Complexity

Pattern: Stack

When the most recent unresolved thing is the one that matters, use a stack. LeetCode 1700. Number of Students Unable to Eat Lunch is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Stack and Queue.

The stack guide has the Python template for the pattern and the 194 LeetCode problems that use it.

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