Problem

Source: 2019 Taiwan TST Round 2

Tags: combinatorics



There are $ n \ge 3 $ puddings in a room. If a pudding $ A $ hates a pudding $ B $, then $ B $ hates $ A $ as well. Suppose the following two conditions holds: 1. Given any four puddings, there are two puddings who like each other. 2. For any positive integer $ m $, if there are $ m $ puddings who like each other, then there exists $ 3 $ puddings (from the other $ n-m $ puddings) that hate each other. Find the smallest possible value of $ n $.