小编zhu*_*008的帖子

字符串中有多少个子字符串？

Why does string x [1:n] have O(n^2) subtrings in the lecture 21 Dynamic Programming III of        
6.006 from MIT? 
Why is not O(2^n)?

这是一个链接[ http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-006-introduction-to-algorithms-fall-2011/lecture-videos/MIT6_006F11_lec21.pdf]