Eight Queens Problem--java algorithm

public class Queen{ //同栏是否有皇后，1表示有 private int [] column; //右上至左下是否有皇后 private int [] rup; //左上至右下是否有皇后 private int [] lup; //解答 private int [] queen; //解答编号 private int num; public Queen(){ column= new int [ 8 + 1 ]; rup= new int [( 2 * 8 )+ 1 ]; lup= new int [( 2 * 8 )+ 1 ]; for ( int i= 1 ;i<= 8 ;i++) column[i]= 0 ; for ( int i= 1 ;i<=( 2 * 8 );i++) rup[i]=lup[i]= 0 ;   //初始定义全部无皇后 queen= new int [ 8 + 1 ]; } public void backtrack( int i){ if (i> 8 ){ showAnswer(); } else { for ( int j= 1 ;j<= 8 ;j++){ if ((column[j]== 0 )&&(rup[i+j]== 0 )&&(lup[i-j+ 8 ]== 0 )){ //若无皇后 queen[i]=j; //设定为占用 column[j]=rup[i+j]=lup[i-j+ 8 ]= 1 ; backtrack(i+ 1 );   //循环调用 column[j]=rup[i+j]=lup[i-j+ 8 ]= 0 ; } } } } protected void showAnswer(){ num++; System.out.println( "\n解答" +num); for ( int y= 1 ;y<= 8 ;y++){ for ( int x= 1 ;x<= 8 ;x++){ if (queen[y]==x){ System.out.print( "Q" ); } else { System.out.print( "." ); } } System.out.println(); } } public static void main(String[]args){ Queen queen= new Queen(); queen.backtrack( 1 ); } }

Eight Queens Problem--java algorithm