File size: 1,380 Bytes
c574d3a |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 |
public class NQueens{
static final int N = 4;
static void print(int board[][]){
for(int i=0; i<N; i++){
for(int j=0;j<N; j++){
System.out.print(board[i][j]+" ");
}
System.out.println();
}
}
// isSafe or not ;
// from left to right
static boolean isSafe(int board[][], int row, int col){
// row on the left side
int i, j;
for(i=0; i<col; i++){
if(board[row][i]==1)
return false;
}
// upper diagonal
for( i=row,j=col; i>=0 && j>=0; i--, j--)
if(board[i][j]==1)
return false;
// lower diagonal
for(i=row,j=col; j>=0 && i<N; i++,j--){
if(board[i][j]==1)
return false;
}
return true;
}
static boolean solve(int board[][], int col){
if(col>=N)
return true;
for(int i=0; i<N; i++){
if(isSafe(board,i,col)){
board[i][col] = 1;
if(solve(board,col+1)==true)
return true;
board[i][col] = 0;
}
}
return false;
}
public static void main(String[] args){
int board[][] = { { 0, 0, 0, 0 },
{ 0, 0, 0, 0 },
{ 0, 0, 0, 0 },
{ 0, 0, 0, 0 } };
if (solve(board, 0) == false) {
System.out.print("Solution does not exist");
}
print(board);
}
}
|