vector binary_search：
http://c.biancheng.net/view/7537.html#:~:text=binary_search%20%28%29%20%E5%87%BD%E6%95%B0%E5%AE%9A%E4%B9%89%E5%9C%A8%20%3Calgorithm%3E,%E5%A4%B4%E6%96%87%E4%BB%B6%E4%B8%AD%EF%BC%8C%E7%94%A8%E4%BA%8E%E6%9F%A5%E6%89%BE%E6%8C%87%E5%AE%9A%E5%8C%BA%E5%9F%9F%E5%86%85%E6%98%AF%E5%90%A6%E5%8C%85%E5%90%AB%E6%9F%90%E4%B8%AA%E7%9B%AE%E6%A0%87%E5%85%83%E7%B4%A0%E3%80%82%20%E8%AF%A5%E5%87%BD%E6%95%B0%E6%9C%89%202%20%E7%A7%8D%E8%AF%AD%E6%B3%95%E6%A0%BC%E5%BC%8F%EF%BC%8C%E5%88%86%E5%88%AB%E4%B8%BA%EF%BC%9A
