Intelligence competition: Coal Transportation by train

It is said that this is a classic problem :( http://coolshell.cn/articles/4429.html)

You are a coal boss in Shanxi province. You have mined 3000 tons of coal in the mining area and need to transport it to the market for sale. there are 1000 kilometers from your mining area to the market, there is a coal-burning train in your hand. This train can only hold up to 1000 tons of coal, and its energy consumption is relatively high-each kilometer consumes one ton of coal. How can you transport the most widely used coal to the market as a programmer?