输入某年某月某日，判断这一天是这一年的第几天？ 1.程序分析：以3月5日为例，应该先把前两个月的加起来，然后再加上5天即本年的第几天，特殊 情况，闰年且输入月份大于3时需考虑多加一天。(What is the day of the year? 1. program analysis: taking March 5th as an example, we should first add up the first two months, and then add 5 days, t