MagicalStringDiv2 | Topcoder Archive

Problem Statement

Magical Girl Illy uses "magical strings" to cast spells. For her, a string X is magical if and only if there exists a positive integer k such that X is composed of k consecutive '>' characters followed by k consecutive '<' characters.
Once Illy picked up a String S. The length of S was even, and each character of S was either '<' or '>'. Illy wants to change S into a magical string. In each step, she can change a single '>' to a '<' or vice versa. Compute and return the smallest number of steps in which she can change S into a magical string.

Definition

Class:: MagicalStringDiv2
Method:: minimalMoves
Parameters:: String
Returns:: int
Method signature:: int minimalMoves(String S)
(be sure your method is public)

Constraints

S will contain between 2 and 50 characters, inclusive.
S will contain even number of characters.
Each character of S will be '<' or '>'.

Examples

```
">><<><"
```
```
Returns: 2
```
She needs to change character 2 (0-based index) from '<' to '>', and character 4 from '>' to '<'.
```
">>>><<<<"
```
```
Returns: 0
```
S is already a magical string, so no changes are needed.
```
"<<>>"
```
```
Returns: 4
```

"<><<<>>>>><<>>>>><>><<<>><><><><<><<<<<><<>>><><><"

Returns: 20

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