N-queens Problem.ipynb

{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "# N-queen problem by backtracking"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "from nQueenClass import nQueenBoard"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [],
   "source": [
    "# helper fuction to print all the solutions and will return the no. of solutions to display\n",
    "\n",
    "def printAllSolutions(myBoardObj):\n",
    "\n",
    "    noOfQueens = myBoardObj.getSize()\n",
    " \n",
    "    # baseCase\n",
    "    if noOfQueens == myBoardObj.QueensCount():\n",
    "        myBoardObj.display()\n",
    "        print(\"\\n\")\n",
    "        return 1\n",
    " \n",
    "    solutions = 0\n",
    "    # place queen in next row\n",
    "    for i in range(noOfQueens):\n",
    "        \n",
    "          #check if it's safely placed in column\n",
    "        if myBoardObj.isSafe(i):\n",
    "            \n",
    "            myBoardObj.MoveToNextRow(i)\n",
    "            #recursive call\n",
    "            solutions += printAllSolutions(myBoardObj) \n",
    "            myBoardObj.RemoveFromCurrentRow()\n",
    " \n",
    "    return solutions"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [],
   "source": [
    "def printAllPossibleSolutions(numberOfQueens):\n",
    "    \n",
    "     #iniltializing the class\n",
    "    ObjBoard = nQueenBoard(numberOfQueens)\n",
    "    \n",
    "    # get total no of solutions after printing them in printAllSolutions(objBoard)\n",
    "    TotalSolutions = printAllSolutions(ObjBoard)\n",
    "    \n",
    "    print('Number of possible solutions -->', TotalSolutions)\n",
    " "
   ]
  },
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    {
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      "Enter the number of queens : 7\n",
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      "\n",
      "Number of possible solutions --> 40\n"
     ]
    }
   ],
   "source": [
    "# main \n",
    "\n",
    "nQueens = int(input('Enter the number of queens : '))\n",
    "print()\n",
    "printAllPossibleSolutions(nQueens)"
   ]
  },
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   "execution_count": null,
   "metadata": {},
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