Create Solution

Solution

@@ -0,0 +1,84 @@
+import java.util.*;
+
+public class Solution
+{
+    public static void main(String args[])
+    {
+        System.out.println(Solution.solveNQueens(4));
+    }
+    public static ArrayList<List<String>> solveNQueens(int n)
+    {
+        ArrayList<List<String>> board=new ArrayList<>();
+        for(int i =0;i<n;i++)
+        {
+            ArrayList<String> sub=new ArrayList<>();
+            for(int j=0;j<n;j++)
+            {
+                sub.add(".");
+
+            }
+            board.add(sub);}
+        ArrayList<List<String>> resultant=new ArrayList<>();
+        Solution.queens(board,0,resultant);
+        return resultant;
+    }
+
+
+
+    public static int queens(ArrayList<List<String>> board,int row,ArrayList<List<String>> resultant)
+    {
+        if(row==(board.size()))
+        {
+            ArrayList<String> subi=new ArrayList<>();
+            for(int p=0;p<board.size();p++)
+            {
+                String res=String.join("",board.get(p));
+                subi.add(res);
+
+            }
+            resultant.add(subi);
+            return 1;
+        }
+        int count=0;
+        for(int col=0;col<board.size();col++)
+        {
+            if(isSafe(board,row,col))
+            {
+                board.get(row).set(col,"Q");
+                count=count+queens(board,(row+1),resultant);
+                board.get(row).set(col,".");
+
+
+            }
+        }
+        return count;
+    }
+    public static boolean isSafe(ArrayList<List<String>> board,int i,int j)
+    {
+        for(int x=0;x<i;x++)
+        {
+            if((board.get(x).get(j)).equals("Q"))
+            {
+                return false;
+            }
+        }
+        int maxLeft=(int)Math.min(i,j);
+        for(int x=1;x<=maxLeft;x++)
+        {
+            if((board.get(i-x).get(j-x)).equals("Q"))
+            {
+                return false;
+            }
+        }
+        int maxRight=(int)Math.min(i,board.size()-j-1);
+        for(int x=1;x<=maxRight;x++)
+        {
+            if((board.get(i-x).get(j+x)).equals("Q"))
+            {
+                return false;
+            }
+        }
+        return true;
+    }
+
+}