MatrixTransforming | Topcoder Archive

Problem Statement

Given two matrices a and b, both composed of zeroes and ones, return the minimal number of operations necessary to transform matrix a into matrix b. An operation consists of flipping (one becomes zero and zero becomes one) all elements of some contiguous 3 x 3 submatrix. If a cannot be transformed into b, return -1.

Definition

Class:: MatrixTransforming
Method:: minPushes
Parameters:: String[], String[]
Returns:: int
Method signature:: int minPushes(String[] a, String[] b)
(be sure your method is public)

Constraints

a will contain between 1 and 50 elements, inclusive.
a and b will contain the same number of elements.
Each element of a will contain between 1 and 50 characters, inclusive.
Each element of b will contain between 1 and 50 characters, inclusive.
All elements of a and b will contain the same number of characters.
Each element of a and b will be contain only zeroes ('0') and ones ('1').

Examples

{"111","111","111"}

{"000","000","000"}

Returns: 1

Flip the entire 3 x 3 matrix.

```
{"1"}
```
```
{"0"}
```
```
Returns: -1
```
No flip can be made here.

{"001","100","100","000","011","010","100","100","010",
"010","010","110","101","101","000","110","000","110"}

{"001","100","011","000","100","010","011","100","101",
"101","010","001","010","010","111","110","111","001"}

Returns: 7

{
"0000",
"0010",
"0000"
}

{
"1001",
"1011",
"1001"
}

Returns: 2

Flip each of the two 3 x 3 submatrices once.

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