算法1

Java 代码

import java.io.*;
class Main{
    static BufferedReader read = new BufferedReader(new InputStreamReader(System.in));
    static char[][] grid;
    static boolean[] dg, udg, col;
    static int n;
    public static void main(String[] args) throws Exception{
        n = Integer.valueOf(read.readLine());
        grid = new char[n][n];
        dg = new boolean[n * 2];  
        udg = new boolean[n * 2]; 
        col = new boolean[n];
        for(int i = 0; i < n; i++){
            for(int j = 0; j < n; j++){
                grid[i][j] = '.';
            }
        }
        dfs(0);
    }

    public static void dfs(int row){
        if(row == n){
            for(int i = 0; i < n; i++) System.out.println(grid[i]);
            System.out.println();
            return;
        }
        for(int i = 0; i < n; i++){
            if(col[i] || dg[row + i] || udg[i - row + n - 1]) continue;
            grid[row][i] = 'Q';
            col[i] = dg[row + i] = udg[i - row + n - 1] = true;
            dfs(row + 1);
            col[i] = dg[row + i] = udg[i - row + n - 1] = false;
            grid[row][i] = '.';
        }

    }
}