MathDB
Linus Tech Tips

Source: AMC 12A #16

November 11, 2021

Problem Statement

An organization has 3030 employees, 2020 of whom have a brand A computer while the other 1010 have a brand B computer. For security, the computers can only be connected to each other and only by cables. The cables can only connect a brand A computer to a brand B computer. Employees can communicate with each other if their computers are directly connected by a cable or by relaying messages through a series of connected computers. Initially, no computer is connected to any other. A technician arbitrarily selects one computer of each brand and installs a cable between them, provided there is not already a cable between that pair. The technician stops once every employee can communicate with each other. What is the maximum possible number of cables used?
<spanclass=latexbold>(A)</span> 190<spanclass=latexbold>(B)</span> 191<spanclass=latexbold>(C)</span> 192<spanclass=latexbold>(D)</span> 195<spanclass=latexbold>(E)</span> 196<span class='latex-bold'>(A)</span>\ 190 \qquad<span class='latex-bold'>(B)</span>\ 191 \qquad<span class='latex-bold'>(C)</span>\ 192 \qquad<span class='latex-bold'>(D)</span>\ 195 \qquad<span class='latex-bold'>(E)</span>\ 196