摘要：
After World War X, a lot of cities have been seriously damaged, and we need to rebuild those cities. However, some materials needed can only be produc 阅读全文
摘要：
Farmer John's cows refused to run in his marathon since he chose a path much too long for their leisurely lifestyle. He therefore wants to find a path 阅读全文
摘要：
There are n houses in the village and some bidirectional roads connecting them. Every day peole always like to ask like this "How far is it if I want 阅读全文