面试题[后缀数组]: 最长重复子串

题目：给定一个字符串，求出最长重复子串。

这个题目可以用后缀数组来解：对后缀数组排好序，这样重复的子串就在相邻的后缀中找就可以了。我的C++代码实现如下：

class Solution
{
public:
    string LongestRepeatingSubstring(string str)
    {
        size_t len = str.size();
        vector<string> SuffixArray(len);
        for (size_t i = 0; i < len; ++i)
            SuffixArray[i] = str.substr(i);

        sort(SuffixArray.begin(), SuffixArray.end());

        size_t maxLen = 0, idx = 0;
        for (size_t i = 0; i < len - 1; ++i)
        {
            size_t curLen = LongestPrefix(SuffixArray[i], SuffixArray[i + 1]);
            if (curLen > maxLen)
            {
                maxLen = curLen;
                idx = i;
            }
        }

        return SuffixArray[idx].substr(0, maxLen);
    }

private:
    size_t LongestPrefix(string str1, string str2)
    {
        size_t len = min(str1.size(), str2.size());
        for (size_t i = 0; i < len; ++i)
            if (str1[i] != str2[i])
                return i;
        return len;
    }
};