N-Queens II

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题目描述：

Follow up for N-Queens problem.
Now, instead outputting board configurations,
return the total number of distinct solutions.

思路：同N Queens一样，是一道题求的结果不同。

public class N_QueensTwo {public static int count=0;public static int solveNQueens(int n)  { String board[][]=new String[n][n]; for(int i=0;i<n;i++) {for(int j=0;j<n;j++){board[i][j]=".";}  } solve(board,n,0); return count; }public static void solve(String board[][],int n,int line) { if(line==n) { count++; } else {//对每一行的每一列进行枚举for(int i=0;i<n;i++){if(check(board,n,line,i)){board[line][i]="Q";}else{continue;}solve(board,n,line+1);board[line][i]=".";} } } public static boolean check(String board[][],int n,int line,int column) { for(int i=line-1;i>=0;i--) {if(board[i][column].equals("Q")){return false;} } for(int i=line-1,j=column-1;i>=0&&j>=0;i--,j--) { if(board[i][j].equals("Q")) { return false; } } for(int i=line-1,j=column+1;i>=0&&j<n;i--,j++) { if(board[i][j].equals("Q")) { return false; } }return true;  }public static void main(String[] args) {Scanner sc=new Scanner(System.in);int n=sc.nextInt();System.out.println(solveNQueens(n));}}

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