DistinctStrings | Topcoder Archive

Problem Statement

Help Donna pick a password!

Her password should have exactly L characters. The letters the password may contain are given in the String letters.

Generate N mutually distinct possible passwords for Donna, so that she can pick one that appeals to her. Return the generated passwords in a String[]

Definition

Class:: DistinctStrings
Method:: generate
Parameters:: int, String, int
Returns:: String[]
Method signature:: String[] generate(int L, String letters, int N)
(be sure your method is public)

Notes

Any valid answer will be accepted.
For the given constraints a valid answer always exists.

Constraints

L will be between 3 and 10, inclusive.
letters will have between 10 and 62 characters, inclusive.
The characters in letters will be a subset of [a-zA-Z0-9] (i.e., letters and digits).
All characters in letters will be mutually distinct.
N will be between 1 and 200, inclusive.

Examples

"qwertyuiopasdfghjklzxcvbnm"

Returns: {"hello", "abcde", "wwwww", "coins", "coder", "digit", "clash", "qwert", "puppy", "kitty" }

We want 10 different password suggestions. Each must be a 5-character string of lowercase letters.

```
3
```
```
"ABCDE02468"
```
```
17
```
```
Returns: {"ABC", "D2E", "DDD", "AAA", "EEE", "024", "042", "204", "240", "402", "420", "4AB", "4EE", "E4E", "ED4", "868", "844" }
```
Here we want 17 distinct password suggestions. Each must have three characters, and each of those must be one of the first five uppercase letters or an even digit.
```
8
```
```
"cdeopPrRtT"
```
```
4
```
```
Returns: {"topcoder", "Topcoder", "docopTer", "receptor" }
```
Case matters. The first two password suggestions are distinct because one starts with a lowercase t and the other with an uppercase T.

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