摘要：
When register on a social network, you are always asked to specify your hobbies in order to find some potential friends with the same hobbies. A socia 阅读全文
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Some scientists took pictures of thousands of birds in a forest. Assume that all the birds appear in the same picture belong to the same tree. You are 阅读全文
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One way that the police finds the head of a gang is to check people's phone calls. If there is a phone call between A and B, we say that A and B is re 阅读全文
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A vertex cover of a graph is a set of vertices such that each edge of the graph is incident to at least one vertex of the set. Now given a graph with 阅读全文
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Input our current position and a destination, an online map can recommend several paths. Now your job is to recommend two paths to your user: one is t 阅读全文
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Indeed there are many different tourist routes from our city to Rome. You are supposed to find your clients the route with the least cost while gainin 阅读全文
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A gas station has to be built at such a location that the minimum distance between the station and any of the residential housing is as far away as po 阅读全文
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For any 4-digit integer except the ones with all the digits being the same, if we sort the digits in non-increasing order first, and then in non-decre 阅读全文