短語詞組短語nonnegative integer solution 非負(fù)整數(shù)解set of nonnegative integer 非負(fù)整數(shù)集nonnegative integer solutions 非負(fù)整數(shù)解nonnegative integer -valued random variable 非負(fù)整值隨機(jī)變量 返回 nonnegative integer