摘要：
StepsOne steps through integer points of the straight line. The length of a step must be nonnegative and can be by one bigger than, equal to, or by on... 阅读全文
摘要：
The ? 1 ? 2 ? ... ? n = k problemThe problemGiven the following formula, one can set operators '+' or '-' instead of each '?', in order to obtain a gi... 阅读全文