Problem Statement
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A square matrix is a grid of NxN numbers. For example, the following is a 3x3 matrix:
4 3 5
2 4 5
0 1 9
One way to represent a matrix of numbers, each of which is between 0 and 9 inclusive, is as a row-major String. To generate the String, simply concatenate all of the elements from the first row followed by the second row and so on, without any spaces. For example, the above matrix would be represented as "435245019". You will be given a square matrix as a row-major String. Your task is to convert it into a String[], where each element represents one row of the original matrix. Element i of the String[] represents row i of the matrix. You should not include any spaces in your return. Hence, for the above String, you would return {"435","245","019"}. If the input does not represent a square matrix because the number of characters is not a perfect square, return an empty String[], {}.
Definition
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Class:
MatrixTool
Method:
convert
Parameters:
String
Returns:
String[]
Method signature:
String[] convert(String s)
(be sure your method is public)
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Constraints
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s will contain between 1 and 50 digits, inclusive.
Examples
0)
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"435245019"
Returns: {"435", "245", "019" }
The example above.
1)
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"9"
Returns: {"9" }
2)
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"0123456789"
Returns: { }
This input has 10 digits, and 10 is not a perfect square.
3)
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"3357002966366183191503444273807479559869883303524"
Returns: {"3357002", "9663661", "8319150", "3444273", "8074795", "5986988", "3303524" }
This problem statement is the exclusive and proprietary property of TopCoder, Inc. Any unauthorized use or reproduction of this information without the prior written consent of TopCoder, Inc. is strictly prohibited. (c)2003, TopCoder, Inc. All rights reserved.
局搞笑的題目。這次中國錦標賽的模擬題比起上次東亞的差的太遠了。解一個吧：
public class MatrixTool 
{
public String[] convert(String s){
int l = s.length();
int sq = new Double(Math.sqrt(l)).intValue();
if(sq*sq!=l)return new String[]{};
String[] result = new String[sq];
for(int i=0;i<sq;i++)
result[i]=s.substring(i*sq,(i+1)*sq);
return result;
}
public static void main(String[] args){
String[] s;
s = new MatrixTool().convert("435245019");
System.out.println(java.util.Arrays.asList(s));
s = new MatrixTool().convert("0123456789");
System.out.println(java.util.Arrays.asList(s));
s = new MatrixTool().convert("3357002966366183191503444273807479559869883303524");
System.out.println(java.util.Arrays.asList(s));
}
}