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bin-vector sphere
import java.util.BitSet;
import java.util.Objects;
import java.util.Scanner;
import java.util.function.Supplier;
import java.util.stream.Stream;
import static java.lang.System.out;
public class BinVectorSphere {
public static void main(String[] args) {
final Scanner scanner = new Scanner(System.in);
out.println("Enter length");
final int length = scanner.nextInt();
if (length < 0) throw new IllegalArgumentException("Length cannot be negative");
scanner.nextLine();
out.println("Enter center");
final BitSet center = readBitVector(length, scanner);
out.println("Enter radius");
final int radius = scanner.nextInt();
if (radius < 0) throw new IllegalArgumentException("Radius cannot be negative");
out.print("S(");
printBits(length, center);
out.println(", " + radius + ") = {");
sphere(length, center, radius)
.takeWhile(Objects::nonNull)
.forEach(vector -> {
out.print('\t');
printBits(length, vector);
out.println();
});
out.println('}');
}
private static BitSet readBitVector(final int length, final Scanner scanner) {
final String line = scanner.nextLine();
if (line.length() != length) throw new IllegalArgumentException("vector should be of " + length + " bits");
final BitSet bitSet = new BitSet(length);
for (int i = 0; i < length; i++) {
final char character = line.charAt(i);
if (character == '1') bitSet.set(i);
else if (character != '0') throw new IllegalArgumentException("A vector should be written using 0s and 1s");
}
return bitSet;
}
private static void printBits(final int length, final BitSet bitSet) {
for (int i = 0; i < length; i++) out.print(bitSet.get(i) ? '1' : '0');
}
private static Stream<BitSet> sphere(final int length, final BitSet center, final int radius) {
return Stream.generate(SphereGenerator.create(length, center, radius));
}
private static final class SphereGenerator implements Supplier<BitSet> {
private final int length;
private final BitSet center;
private BitSet radiusVector;
public SphereGenerator(final int length, final BitSet center, final BitSet radiusVector) {
this.length = length;
this.center = center;
this.radiusVector = radiusVector;
}
@Override
public BitSet get() {
if (radiusVector == null) return null;
final BitSet result = (BitSet) center.clone();
result.xor(radiusVector);
incrementRadiusVector();
return result;
}
private void incrementRadiusVector() {
for (int index = length - 2; index >= 0; --index) {
if (radiusVector.get(index)) { // try move to the right
final int nextIndex;
if (radiusVector.get(nextIndex = index + 1)) {
continue; // cannot move to the right
}
radiusVector.clear(index);
radiusVector.set(nextIndex);
return;
}
}
radiusVector = null;
}
public static Supplier<BitSet> create(final int length, final BitSet center, final int radius) {
if (radius > length) throw new IllegalArgumentException("Radius cannot be greater than n");
BitSet radiusVector = new BitSet();
for (int i = 0; i < radius; i++) radiusVector.set(i);
return new SphereGenerator(length, center, radiusVector);
}
}
}
Enter length
6
Enter center
000000
Enter radius
3
S(000000, 3) = {
111000
110100
110010
110001
101001
100101
100011
010011
001011
000111
}
Enter length
10
Enter center
1100110011
Enter radius
5
S(1100110011, 5) = {
0011010011
0011100011
0011111011
0011110111
0011110001
0011110010
0010010010
0010100010
0010111010
0010110110
0010110000
0001110000
0000010000
0000100000
0000111000
0000110100
0110110100
0101110100
0100010100
0100100100
0100111100
1000111100
1110111100
1101111100
1100011100
1100101100
}
Enter length
20
Enter center
10011010100101010110
Enter radius
7
S(10011010100101010110, 7) = {
01100100100101010110
01100111100101010110
01100110000101010110
01100110110101010110
01100110101101010110
01100110100001010110
01100110100111010110
01100110100100010110
01100110100101110110
01100110100101000110
01100110100101011110
01100110100101010010
01100110100101010100
01100110100101010111
01100000100101010111
01100011100101010111
01100010000101010111
01100010110101010111
01100010101101010111
01100010100001010111
01100010100111010111
01100010100100010111
01100010100101110111
01100010100101000111
01100010100101011111
01100010100101010011
01100010100101010101
01101110100101010101
01101000100101010101
01101011100101010101
01101010000101010101
01101010110101010101
01101010101101010101
01101010100001010101
01101010100111010101
01101010100100010101
01101010100101110101
01101010100101000101
01101010100101011101
01101010100101010001
01110010100101010001
01111110100101010001
01111000100101010001
01111011100101010001
01111010000101010001
01111010110101010001
01111010101101010001
01111010100001010001
01111010100111010001
01111010100100010001
01111010100101110001
01111010100101000001
01111010100101011001
01001010100101011001
01010010100101011001
01011110100101011001
01011000100101011001
01011011100101011001
01011010000101011001
01011010110101011001
01011010101101011001
01011010100001011001
01011010100111011001
01011010100100011001
01011010100101111001
01011010100101001001
00111010100101001001
00001010100101001001
00010010100101001001
00011110100101001001
00011000100101001001
00011011100101001001
00011010000101001001
00011010110101001001
00011010101101001001
00011010100001001001
00011010100111001001
00011010100100001001
00011010100101101001
11011010100101101001
10111010100101101001
10001010100101101001
10010010100101101001
10011110100101101001
10011000100101101001
10011011100101101001
10011010000101101001
10011010110101101001
10011010101101101001
10011010100001101001
10011010100111101001
10011010100100101001
}
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