2014西安网络预选赛1002（后缀数组求第K大的子串）hdu5008

Boring String Problem

Time Limit: 6000/3000 MS (Java/Others) Memory Limit: 65536/65536 K (Java/Others)

Total Submission(s): 272 Accepted Submission(s): 65



Problem Description

In this problem, you are given a string s and q queries.

For each query, you should answer that when all distinct substrings of string s were sorted lexicographically, which one is the k-th smallest.

A substring si...j of the string s = a1a2 ...an(1 ≤ i ≤ j ≤ n) is the string aiai+1 ...aj. Two substrings sx...y and sz...w are cosidered to be distinct if sx...y ≠
Sz...w

Input

The input consists of multiple test cases.Please process till EOF.

Each test case begins with a line containing a string s(|s| ≤ 105) with only lowercase letters.

Next line contains a postive integer q(1 ≤ q ≤ 105), the number of questions.

q queries are given in the next q lines. Every line contains an integer v. You should calculate the k by k = (l⊕r⊕v)+1(l, r is the output of previous question, at the beginning of each case l = r = 0, 0 < k < 263, “⊕” denotes exclusive or)

Output

For each test case, output consists of q lines, the i-th line contains two integers l, r which is the answer to the i-th query. (The answer l,r satisfies that sl...r is the k-th smallest and if there are several l,r available, ouput l,r which with
the smallest l. If there is no l,r satisfied, output “0 0”. Note that s1...n is the whole string)

Sample Input

aaa
4
0
2
3
5

Sample Output

1 1
1 3
1 2
0 0

题意：找出第k大的子串，有多种情况要取l最小的一个

思路：比赛的时候看完题目以后大概知道是后缀数组，就没细想了，因为还有其它过的人更多的题没做出来= =

首先注意后缀数组可以求出到第i个后缀一共有多少种不同的子串

先不考虑前面的影响，而第i个后缀不同的子串的个数就等于在该后缀上找前缀的个数，就等于该后缀的长度，即cnt=n-sa[i]

而这个cnt是包含了与上一个名次的后缀前面一样的串的个数，所以还要减去这部分（恰好等于height[i]），即cnt=cnt - height[i]

然后对于查询，只需要二分找到第一个满足的sa[i]，那么就可以从sa[i]开始往后枚举最小的下标，因为后面可能存在一样的串且下标更小