MathDB
combinatorics

Source: Switzerland Final Round 2021 P7

February 24, 2021
combinatorics

Problem Statement

Let mnm \ge n be positive integers. Frieder is given mnmn posters of Linus with different integer dimensions of k×lk \times l with 1km1 \ge k \ge m and 1ln1 \ge l \ge n. He must put them all up one by one on his bedroom wall without rotating them. Every time he puts up a poster, he can either put it on an empty spot on the wall or on a spot where it entirely covers a single visible poster and does not overlap any other visible poster. Determine the minimal area of the wall that will be covered by posters.