Using a binary search tree or dividing the string into segments as long as the square root of the length of the string will solve the problem.
Using a binary search tree or dividing the string into segments as long as the square root of the length of the string will solve the problem.
用一个二叉搜索树或者将串切分成长度的平方根那么长的小段都可以解决这个问题。