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Merge pull request #74 from olepoeschl/generator-for-distributed
Unified Constellations Generator for CPUSolver and GPUSolver
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src/main/java/de/nqueensfaf/impl/ConstellationsGenerator.java
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| package de.nqueensfaf.impl; | ||
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| import java.util.ArrayList; | ||
| import java.util.HashSet; | ||
| import java.util.function.Consumer; | ||
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| import static de.nqueensfaf.impl.SolverUtils.*; | ||
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| public class ConstellationsGenerator { | ||
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| private ArrayList<Constellation> constellations; | ||
| private int n, presetQueens; | ||
| private int L, mask, LD, RD, subConstellationsCounter; | ||
| private HashSet<Integer> ijklList; | ||
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| public ConstellationsGenerator(int n, int presetQueens) { | ||
| this.n = n; | ||
| this.presetQueens = presetQueens; | ||
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| L = (1 << (n - 1)); | ||
| mask = (L << 1) - 1; | ||
| } | ||
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| public ArrayList<Constellation> generate(){ | ||
| return generate(null); | ||
| } | ||
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| public ArrayList<Constellation> generate(Consumer<Constellation> constellationConsumer){ | ||
| generateIjkls(); | ||
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| constellations = new ArrayList<Constellation>(); | ||
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| int i, j, k, l, ld, rd, col, currentSize = 0; | ||
| for (int ijkl : ijklList) { | ||
| ijkl = jAsMin(n, ijkl); | ||
| i = geti(ijkl); | ||
| j = getj(ijkl); | ||
| k = getk(ijkl); | ||
| l = getl(ijkl); | ||
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| // counts all subconstellations | ||
| subConstellationsCounter = 0; | ||
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| // fill up the board with preQueens queens and generate corresponding variables | ||
| // ld, rd, col, start_queens_ijkl for each constellation | ||
| // occupy the board corresponding to the queens on the borders of the board | ||
| // we are starting in the first row that can be free, namely row 1 | ||
| ld = (L >>> (i - 1)) | (1 << (n - k)); | ||
| rd = (L >>> (i + 1)) | (1 << (l - 1)); | ||
| col = 1 | L | (L >>> i) | (L >>> j); | ||
| // occupy diagonals of the queens j k l in the last row | ||
| // later we are going to shift them upwards the board | ||
| LD = (L >>> j) | (L >>> l); | ||
| RD = (L >>> j) | (1 << k); | ||
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| // generate all subconstellations | ||
| placePresetQueens(ld, rd, col, k, l, 1, j == n - 1 ? 3 : 4); | ||
| currentSize = constellations.size(); | ||
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| // jkl and sym and start are the same for all subconstellations | ||
| for (int a = 0; a < subConstellationsCounter; a++) { | ||
| var c = constellations.get(currentSize - a - 1); | ||
| c.setStartIjkl(c.getStartIjkl() | ijkl); | ||
| c.setId(currentSize - a - 1); | ||
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| if(constellationConsumer != null) | ||
| constellationConsumer.accept(constellations.get(currentSize - a - 1)); | ||
| } | ||
| } | ||
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| return constellations; | ||
| } | ||
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| public ArrayList<Constellation> generateSubConstellations(ArrayList<Constellation> baseConstellations){ | ||
| constellations = new ArrayList<Constellation>(); | ||
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| int currentSize; | ||
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| for(var bc : baseConstellations) { | ||
| // counts all subconstellations | ||
| subConstellationsCounter = 0; | ||
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| placePresetQueens(bc.getLd(), bc.getRd(), bc.getCol(), getk(bc.getIjkl()), getl(bc.getIjkl()), | ||
| bc.getStartIjkl() >> 20, bc.getStartIjkl() >> 20); // from row start to row presetQueens | ||
| currentSize = constellations.size(); | ||
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| // jkl and sym and start are the same for all subconstellations | ||
| for (int a = 0; a < subConstellationsCounter; a++) { | ||
| var c = constellations.get(currentSize - a - 1); | ||
| c.setStartIjkl(c.getStartIjkl() | bc.getIjkl()); | ||
| c.setId(bc.getId()); | ||
| } | ||
| } | ||
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| return constellations; | ||
| } | ||
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| private void generateIjkls() { | ||
| ijklList = new HashSet<Integer>(); | ||
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| // half of n rounded up | ||
| final int halfN = (n + 1) / 2; | ||
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| // calculate starting constellations for no Queens in corners | ||
| for (int j = 1; j < halfN; j++) { // go through last row | ||
| for (int l = j + 1; l < n - 1; l++) { // go through last col | ||
| for (int k = n - j - 2; k > 0; k--) { // go through first col | ||
| if (k == l) // skip if occupied | ||
| continue; | ||
| for (int i = j + 1; i < n - 1; i++) { // go through first row | ||
| if (i == n - 1 - l || i == k) // skip if occupied | ||
| continue; | ||
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| if (!checkRotations(n, ijklList, i, j, k, l)) { | ||
| // if no rotation-symmetric starting constellation is found | ||
| ijklList.add(toIjkl(i, j, k, l)); | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
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| // calculating start constellations with the first Queen on the corner square | ||
| // (0,0) | ||
| for (int k = 1; k < n - 2; k++) { // j is idx of Queen in last row | ||
| for (int i = k + 1; i < n - 1; i++) { // l is idx of Queen in last col | ||
| // always add the constellation, we can not accidently get symmetric ones | ||
| ijklList.add(toIjkl(i, n - 1, k, n - 1)); | ||
| } | ||
| } | ||
| } | ||
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| // generate sub constellations for each starting constellation | ||
| private void placePresetQueens(int ld, int rd, int col, int k, int l, int row, int queens) { | ||
| // in row k and l just go further | ||
| if (row == k || row == l) { | ||
| placePresetQueens(ld << 1, rd >>> 1, col, k, l, row + 1, queens); | ||
| return; | ||
| } | ||
| // add queens until we have preQueens queens | ||
| if (queens == presetQueens) { | ||
| // add the subconstellations to the list | ||
| constellations.add(new Constellation(0, ld, rd, col, row << 20, -1)); | ||
| subConstellationsCounter++; | ||
| return; | ||
| } | ||
| // if not done or row k or l, just place queens and occupy the board and go | ||
| // further | ||
| else { | ||
| int free = (~(ld | rd | col | (LD >>> (n - 1 - row)) | (RD << (n - 1 - row)))) & mask; | ||
| int bit; | ||
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| while (free > 0) { | ||
| bit = free & (-free); | ||
| free -= bit; | ||
| placePresetQueens((ld | bit) << 1, (rd | bit) >>> 1, col | bit, k, l, row + 1, queens + 1); | ||
| } | ||
| } | ||
| } | ||
| } |
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