[HaBo]

import java.util.Random;

public class SudokuGen {

	static class Matrix<T> {
		private T[][] matrix;
		private int linePointer=0;
		public Matrix(T[][] matrix) { 
			this.matrix=matrix;			
		}
		public void add(T[] row) {
			this.matrix[linePointer] = row;
			linePointer++;
		}
		public void switchRows(int i,int j) {
			T[] tmp = this.matrix[i];
			this.matrix[i] = this.matrix[j];
			this.matrix[j] = tmp;
		}
		public void switchCols(int i,int j) {
			T tmp = null;
			for(int x=0;x<matrix.length;x++) {
				tmp = this.matrix[x][i];
				this.matrix[x][i] = this.matrix[x][j];
				this.matrix[x][j] = tmp;
			}
		}
		public void print() {
			for(int i=0;i<10;i++)System.out.print("----");
			System.out.println();
			for(int i=0;i<matrix.length;i++) {
				System.out.print("|| ");
				for(int j=0;j<matrix[i].length;j++) {
					if((j+1)%3==0)System.out.print(matrix[i][j]+" || ");
					else System.out.print(matrix[i][j]+" | ");
				}
				System.out.println();
				if((i+1)%3==0) {
					for(int x=0;x<10;x++)System.out.print("----");
					System.out.println();
				}
			}
		}
	}

	public static void main(String[] args) {
		Matrix<Integer> field=new Matrix<Integer>(new Integer[9][9]);
		Integer[] row = {1,2,3,4,5,6,7,8,9};
		Random zufall=new Random();
		
		// (1) Add initial line
		field.add(row);
		
		// (2) Fill field with values
		for(int i=1;i<9;i++) {
			row=(i%3==0)?shiftInteger(row,4):shiftInteger(row,3);
			field.add(row);
		}
		
		// (3) Mix it, baby
		for(int i=0;i<zufall.nextInt(1000);i++) {
			int nextInt = zufall.nextInt(9);
			field.switchCols(nextInt, calcNextInt(nextInt,zufall));
			nextInt = zufall.nextInt(9);
			field.switchRows(nextInt, calcNextInt(nextInt,zufall));
		}
		
		// (4) I know you wanne print that...
		field.print();
	}
	
	private static int calcNextInt(int nextInt, Random zufall) {
		switch(nextInt%3) {
		case 0:
			return nextInt+zufall.nextInt(3);
		case 1: 
			int sign=(zufall.nextInt(10)>5)?-1:1;
			return nextInt+sign*zufall.nextInt(2);
		case 2: 
			return nextInt-zufall.nextInt(3);
		}
		return 0;
	}
	
	private static Integer[] shiftInteger(Integer[] arr,int shift) {
		Integer[] newRow = new Integer[9];
		for(int i=0,j=shift;i<9;i++,j++) {
			if(j==9)j=0;
			newRow[i] = arr[j];
		}
		return newRow;
	}

}