People check out the newly opened Second Avenue Subway 86th Street station in New York on Jan. 1 in New York City. (AP Photo/Craig Ruttle) This is your first of three free stories this month. Become a ...
Each metro line usually has its own color on the map. For obvious reasons, these colors should be maximally different. Suppose a new metro line is built. We now explain a strategy to choose the color ...
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