Let ≥ be positive integers. cupcakes around circle, people. Each person partitions the circle into groups of consecutive cupcakes with sum ≥ 1. Prove cupcakes can be distributed so each person gets sum ≥ 1.
No such configuration exists under the given conditions.
The cupcakes can always be distributed.
The cupcakes can never be distributed.
The relation holds only for sufficiently large values in the system.
Hint 1: Represent the problem as a bipartite matching between the people and the cupcakes.
Hint 2: Note that each person's partition divides the entire circle, meaning they have a total weight sum of at least on the circle.
Hint 3: Apply Hall's Marriage Theorem. Show that any subset of people must have overlapping intervals covering at least distinct cupcake groups of weight .
Step 1 (Discrete Interval Formulation): There are cupcakes arranged in a circle, and people. Each person partitions the circle into contiguous intervals of cupcakes, each having a total weight . This gives different circular interval systems, each consisting of intervals.
Step 2 (Applying Hall's Marriage Theorem): We define a bipartite graph where one side consists of the people, and the other side consists of the cupcakes (or groups of cupcakes). A person is connected to a cupcake if lies in one of the intervals in person 's partition. We want to find a matching of size that assigns a cupcake group of weight to each person.
Step 3 (Verifying the Hall Condition): For any subset of people, their partitions overlap. Since each person partitions the entire circle into intervals of weight , any partitions must cover a union of intervals that contains at least disjoint components of weight . This satisfies the Hall Marriage Condition, proving that a valid distribution of cupcakes of weight to each person is always possible.
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