ChangingString | Topcoder Archive

Problem Statement

You are given two Strings A and B that have the same length and contain only lowercase letters ('a'-'z'). The distance between two letters is defined as the absolute value of their difference. The distance between A and B is defined as the sum of the differences between each letter in A and the letter in B at the same position. For example, the distance between "abcd" and "bcda" is 6 (1 + 1 + 1 + 3).

You must change exactly K characters in A into other lowercase letters. Return the minimum possible distance between A and B after you perform that change.

Definition

Class:: ChangingString
Method:: distance
Parameters:: String, String, int
Returns:: int
Method signature:: int distance(String A, String B, int K)
(be sure your method is public)

Constraints

A and B will each contain between 1 and 50 characters, inclusive.
K will be between 1 and the length of A, inclusive.
A and B will contain the same number of characters.
A and B will contain only lowercase letters ('a' - 'z').

Examples

```
"ab"
```
```
"ba"
```
```
2
```
```
Returns: 0
```
The minimum distance (equal to 0) can be achieved when we change 'a' to 'b' and 'b' to 'a'.
```
"aa"
```
```
"aa"
```
```
2
```
```
Returns: 2
```
We must change both letters 'a' to some other letters. Changing them to 'b' results in the smallest distance.
```
"aaa"
```
```
"baz"
```
```
1
```
```
Returns: 1
```

"fdfdfdfdfdsfabasd"

"jhlakfjdklsakdjfk"

Returns: 24

```
"aa"
```
```
"bb"
```
```
2
```
```
Returns: 0
```

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