cf补题
线段树4题：
https://github.com/YANGRUZHAO/ACM/blob/17fa8710698daa881c7f2fbd84897f4ae6de2f31/%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84/%E7%BA%BF%E6%AE%B5%E6%A0%91%E7%A6%BB%E7%BA%BF%E5%A4%84%E7%90%86(hdu4630).cpp
https://github.com/YANGRUZHAO/ACM/blob/17fa8710698daa881c7f2fbd84897f4ae6de2f31/%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84/%E5%8A%BF%E8%83%BD%E7%BA%BF%E6%AE%B5%E6%A0%91(cf920f).cpp
https://github.com/YANGRUZHAO/ACM/blob/17fa8710698daa881c7f2fbd84897f4ae6de2f31/%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84/%E6%9D%83%E5%80%BC%E7%BA%BF%E6%AE%B5%E6%A0%91(hdu5249).cpp
https://github.com/YANGRUZHAO/ACM/blob/17fa8710698daa881c7f2fbd84897f4ae6de2f31/%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84/%E5%8A%A8%E6%80%81%E5%BC%80%E7%82%B9%E7%A6%BB%E6%95%A3(cf915e).cpp
最近事情较多，时间安排不是很好；需改正。
