Create NQueen_Problem.java

N Queen problem using java Ishaan28malik#1959

Java_Programs-master/NQueen_Problem.java

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+//N Queen problem using java #1959
+class NQueen_Problem{
+    public static boolean isSafe(char chessBoard[][],int row,int col){
+          //vertical up
+          for(int i=row-1;i>=0;i--){
+            if(chessBoard[i][col]=='Q'){
+                return false;
+            }
+          }
+          //left diag up
+          for(int i=row-1,j=col-1;i>=0 && j>=0;i--,j--){
+            if(chessBoard[i][j]=='Q'){
+                return false;
+            }
+        }
+        //right diag up
+        for(int i=row-1,j=col+1;i>=0 && j<chessBoard.length;i--,j++){
+          if(chessBoard[i][j]=='Q'){
+              return false;
+    }
+}
+      return true;
+}
+    public static void nQueen(char chessBoard[][], int row){
+        //Base case
+        if(row==chessBoard.length){
+            printBoard(chessBoard);
+            return;
+        }  
+        //cloumn loop
+          for(int j=0;j<chessBoard.length;j++){
+            if (isSafe(chessBoard,row,j)){
+            chessBoard[row][j]='Q';
+            nQueen(chessBoard, row+1);  //function call
+            chessBoard[row][j]='x';  //backtrack
+            }
+          }
+    }
+    public static void printBoard(char chessBoard[][]){
+        System.out.println("----Chess-Board----");
+        for(int i=0;i<chessBoard.length;i++){
+        for(int j=0;j<chessBoard.length;j++){
+            System.out.print(chessBoard[i][j]+" ");
+        }
+        System.out.println();
+    }
+}