Score : 300 points
You are given a string s. Among the different substrings of s, print the K-th lexicographically smallest one.
A substring of s is a string obtained by taking out a non-empty contiguous part in s.
For example, if s = ababc
, a
, bab
and ababc
are substrings of s, while ac
, z
and an empty string are not.
Also, we say that substrings are different when they are different as strings.
Let X = x_{1}x_{2}...x_{n} and Y = y_{1}y_{2}...y_{m} be two distinct strings. X is lexicographically larger than Y if and only if Y is a prefix of X or x_{j} > y_{j} where j is the smallest integer such that x_{j} \neq y_{j}.
Input is given from Standard Input in the following format:
s K
Print the K-th lexicographically smallest substring of K.
aba 4
b
s has five substrings: a
, b
, ab
, ba
and aba
.
Among them, we should print the fourth smallest one, b
.
Note that we do not count a
twice.
atcoderandatcodeer 5
andat
z 1
z