课下2刷
<span style="color:rgba(0, 0, 0, 0.87);font-family:Lato, " font-size:14px;text-wrap-mode:wrap;background-color:#ffffff;"="">2219:</span><a href="http://www.ddcoj.com/problem.php?id=2219" target="_blank" style="box-sizing:inherit;color:#013093;text-decoration-line:none;background-color:#FFFFFF;font-family:Lato, " font-size:14px;text-wrap-mode:wrap;"="">【入门】统计每个月兔子的总数  递归 递推</a><br style="box-sizing:inherit;color:rgba(0, 0, 0, 0.87);font-family:Lato, " font-size:14px;text-wrap-mode:wrap;background-color:#ffffff;"=""> <span style="color:rgba(0, 0, 0, 0.87);font-family:Lato, " font-size:14px;text-wrap-mode:wrap;background-color:#ffffff;"="">2144:</span><a href="http://www.ddcoj.com/problem.php?id=2144" target="_blank" style="box-sizing:inherit;color:#013093;text-decoration-line:none;background-color:#FFFFFF;font-family:Lato, " font-size:14px;text-wrap-mode:wrap;"="">【入门】求S的值  函数问题</a><br style="box-sizing:inherit;color:rgba(0, 0, 0, 0.87);font-family:Lato, " font-size:14px;text-wrap-mode:wrap;background-color:#ffffff;"=""> <span style="color:rgba(0, 0, 0, 0.87);font-family:Lato, " font-size:14px;text-wrap-mode:wrap;background-color:#ffffff;"="">2172:</span><a href="http://www.ddcoj.com/problem.php?id=2172" target="_blank" style="box-sizing:inherit;color:#013093;text-decoration-line:none;background-color:#FFFFFF;font-family:Lato, " font-size:14px;text-wrap-mode:wrap;"="">【入门】求s=a+aa+aaa+aaaa+aa...a的值  函数问题 递归</a><br style="box-sizing:inherit;color:rgba(0, 0, 0, 0.87);font-family:Lato, " font-size:14px;text-wrap-mode:wrap;background-color:#ffffff;"=""> <span style="color:rgba(0, 0, 0, 0.87);font-family:Lato, " font-size:14px;text-wrap-mode:wrap;background-color:#ffffff;"="">2124:</span><a href="http://www.ddcoj.com/problem.php?id=2124" target="_blank" style="box-sizing:inherit;color:#013093;text-decoration-line:none;background-color:#FFFFFF;font-family:Lato, " font-size:14px;text-wrap-mode:wrap;"="">【入门】求1/1+1/2+2/3+3/5+5/8+8/13+13/21……的前n项的和  函数问题</a>
课后作业：