LinenCenterEasy | Topcoder Archive

Problem Statement

A few days ago, you won a tour of a textile factory. (Chocolate factory tours were deemed too risky to children and therefore banned). As everyone knows, textile is made of strings, so it's time to solve a string problem!

You are given a String S of length L. For any string T, we can now define its covering number c(T) as the maximum number of non-overlapping occurrences of S in T. Each occurrence must be a contiguous substring of T, and they may not share any letters.

Examples:
If S="ab", we have c("xyz")=0 and c("ababxab")=3.
If S="aaa", we have c("aa")=0 and c("aaaaaa")=2.

In addition to S, you are given two ints N and K.

Consider all strings with the following properties:

Each character of the string is a lowercase English letter ('a'-'z').
The length of the string is between L*K and L*K+N, inclusive.
The covering number of the string is exactly K.

Let X be the number of strings with the above properties. Since X may be large, compute and return the value (X modulo 1,000,000,009).

Definition

Class:: LinenCenterEasy
Method:: countStrings
Parameters:: String, int, int
Returns:: int
Method signature:: int countStrings(String S, int N, int K)
(be sure your method is public)

Constraints

N will be between 0 and 50, inclusive.
K will be between 0 and 50, inclusive.
L will be between 1 and 50, inclusive.
S will contain exactly L characters.
S will contain only lowercase English letters.

Examples

```
"xy"
```
```
2
```
```
1
```
```
Returns: 2079
```
There are 2027 strings of length 4, 52 strings of length 3 and one string of length 2 containing "xy" as a substring. One of them, "xyxy", has covering number 2, so we don't count it.
```
"q"
```
```
2
```
```
1
```
```
Returns: 1926
```
We're counting strings containing exactly one character 'q' and at most two other characters. There's one such string of length 1 ("q"), 2*25=50 of length 2 and 3*25^2=1875 of length 3.
```
"ababab"
```
```
5
```
```
4
```
```
Returns: 527166180
```
Watch out for integer overflows and make sure you are using the correct modulus!
```
"fgcdx"
```
```
10
```
```
3
```
```
Returns: 586649223
```

"ghjhhhgjhjhgjhghghjhjg"

Returns: 192161304

"pdpfrpfdfdpfdpfdpfpdfldfpfldpfe"

Returns: 164673990

```
"a"
```
```
7
```
```
0
```
```
Returns: 357828722
```

"eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee"

Returns: 960113657

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