摘要： Give you a tree, can you draw the tree with minimum strokes without overlapping? Noted that it is ok if two strokes intersect at one point. Here we de 阅读全文

摘要： Bessie's been appointed the new watch-cow for the farm. Every night, it's her job to walk across the farm and make sure that no evildoers are doing an 阅读全文

摘要： My little sister had a beautiful necklace made of colorful beads. Two successive beads in the necklace shared a common color at their meeting point. T 阅读全文