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Copy pathQueens.java
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45 lines (43 loc) · 1.57 KB
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import java.io.*;
class Queens {
final boolean available = true;
final int squares = 5, norm = squares - 1;
int[] positionInRow = new int[squares];
boolean[] column = new boolean[squares];
boolean[] leftDiagonal = new boolean[squares*2 - 1];
boolean[] rightDiagonal = new boolean[squares*2 - 1];
int howMany = 0;
Queens() {
for (int i = 0; i < squares; i++) {
positionInRow[i] = -1;
column[i] = available;
}
for (int i = 0; i < squares*2 - 1; i++)
leftDiagonal[i] = rightDiagonal[i] = available;
}
void printBoard(PrintStream out) {
//.........
}
void putQueen(int row) {
for (int col = 0; col < squares; col++)
if (column[col] == available &&
leftDiagonal [row+col] == available &&
rightDiagonal[row-col+norm] == available) {
positionInRow[row] = col;
column[col] = !available;
leftDiagonal[row+col] = !available;
rightDiagonal[row-col+norm] = !available;
if (row < squares-1)
putQueen(row+1);
else printBoard(System.out);
column[col] = available;
leftDiagonal[row+col] = available;
rightDiagonal[row-col+norm] = available;
}
}
public static void main(String args[]) {
Queens queens = new Queens();
queens.putQueen(0);
System.out.println(queens.howMany + " solutions found.");
}
}