sudokugenerator.cpp
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#include <iostream> #include <algorithm> #include <ctime> #include <cstdlib> #include <fstream> #include <sstream> #include <string> #include <vector> #define UNASSIGNED 0 using namespace std; class Sudoku { private: int grid[9][9]; int solnGrid[9][9]; int guessNum[9]; int gridPos[81]; int difficultyLevel; bool grid_status; public: Sudoku (); Sudoku (string, bool row_major=true); void createSeed(); void printGrid(); bool solveGrid(); string getGrid(); void countSoln(int &number); void genPuzzle(); bool verifyGridStatus(); void printSVG(string); void calculateDifficulty(); int branchDifficultyScore(); }; // START: Get grid as string in row major order string Sudoku::getGrid() { string s = ""; for(int row_num=0; row_num<9; ++row_num) { for(int col_num=0; col_num<9; ++col_num) { s = s + to_string(grid[row_num][col_num]); } } return s; } // END: Get grid as string in row major order // START: Generate random number int genRandNum(int maxLimit) { return rand()%maxLimit; } // END: Generate random number // START: Create seed grid void Sudoku::createSeed() { this->solveGrid(); // Saving the solution grid for(int i=0;i<9;i++) { for(int j=0;j<9;j++) { this->solnGrid[i][j] = this->grid[i][j]; } } } // END: Create seed grid // START: Intialising Sudoku::Sudoku() { // initialize difficulty level this->difficultyLevel = 0; // Randomly shuffling the array of removing grid positions for(int i=0;i<81;i++) { this->gridPos[i] = i; } random_shuffle(this->gridPos, (this->gridPos) + 81, genRandNum); // Randomly shuffling the guessing number array for(int i=0;i<9;i++) { this->guessNum[i]=i+1; } random_shuffle(this->guessNum, (this->guessNum) + 9, genRandNum); // Initialising the grid for(int i=0;i<9;i++) { for(int j=0;j<9;j++) { this->grid[i][j]=0; } } grid_status = true; } // END: Initialising // START: Custom Initialising with grid passed as argument Sudoku::Sudoku(string grid_str, bool row_major) { if(grid_str.length() != 81) { grid_status=false; return; } // First pass: Check if all cells are valid for(int i=0; i<81; ++i) { int curr_num = grid_str[i]-'0'; if(!((curr_num == UNASSIGNED) || (curr_num > 0 && curr_num < 10))) { grid_status=false; return; } if(row_major) grid[i/9][i%9] = curr_num; else grid[i%9][i/9] = curr_num; } // Second pass: Check if all columns are valid for (int col_num=0; col_num<9; ++col_num) { bool nums[10]={false}; for (int row_num=0; row_num<9; ++row_num) { int curr_num = grid[row_num][col_num]; if(curr_num!=UNASSIGNED && nums[curr_num]==true) { grid_status=false; return; } nums[curr_num] = true; } } // Third pass: Check if all rows are valid for (int row_num=0; row_num<9; ++row_num) { bool nums[10]={false}; for (int col_num=0; col_num<9; ++col_num) { int curr_num = grid[row_num][col_num]; if(curr_num!=UNASSIGNED && nums[curr_num]==true) { grid_status=false; return; } nums[curr_num] = true; } } // Fourth pass: Check if all blocks are valid for (int block_num=0; block_num<9; ++block_num) { bool nums[10]={false}; for (int cell_num=0; cell_num<9; ++cell_num) { int curr_num = grid[((int)(block_num/3))*3 + (cell_num/3)][((int)(block_num%3))*3 + (cell_num%3)]; if(curr_num!=UNASSIGNED && nums[curr_num]==true) { grid_status=false; return; } nums[curr_num] = true; } } // Randomly shuffling the guessing number array for(int i=0;i<9;i++) { this->guessNum[i]=i+1; } random_shuffle(this->guessNum, (this->guessNum) + 9, genRandNum); grid_status = true; } // END: Custom Initialising // START: Verification status of the custom grid passed bool Sudoku::verifyGridStatus() { return grid_status; } // END: Verification of the custom grid passed // START: Printing the grid void Sudoku::printGrid() { for(int i=0;i<9;i++) { for(int j=0;j<9;j++) { if(grid[i][j] == 0) cout<<"."; else cout<<grid[i][j]; cout<<"|"; } cout<<endl; } cout<<"\nDifficulty of current sudoku(0 being easiest): "<<this->difficultyLevel; cout<<endl; } // END: Printing the grid // START: Helper functions for solving grid bool FindUnassignedLocation(int grid[9][9], int &row, int &col) { for (row = 0; row < 9; row++) { for (col = 0; col < 9; col++) { if (grid[row][col] == UNASSIGNED) return true; } } return false; } bool UsedInRow(int grid[9][9], int row, int num) { for (int col = 0; col < 9; col++) { if (grid[row][col] == num) return true; } return false; } bool UsedInCol(int grid[9][9], int col, int num) { for (int row = 0; row < 9; row++) { if (grid[row][col] == num) return true; } return false; } bool UsedInBox(int grid[9][9], int boxStartRow, int boxStartCol, int num) { for (int row = 0; row < 3; row++) { for (int col = 0; col < 3; col++) { if (grid[row+boxStartRow][col+boxStartCol] == num) return true; } } return false; } bool isSafe(int grid[9][9], int row, int col, int num) { return !UsedInRow(grid, row, num) && !UsedInCol(grid, col, num) && !UsedInBox(grid, row - row%3 , col - col%3, num); } // END: Helper functions for solving grid // START: Modified Sudoku solver bool Sudoku::solveGrid() { int row, col; // If there is no unassigned location, we are done if (!FindUnassignedLocation(this->grid, row, col)) return true; // success! // Consider digits 1 to 9 for (int num = 0; num < 9; num++) { // if looks promising if (isSafe(this->grid, row, col, this->guessNum[num])) { // make tentative assignment this->grid[row][col] = this->guessNum[num]; // return, if success, yay! if (solveGrid()) return true; // failure, unmake & try again this->grid[row][col] = UNASSIGNED; } } return false; // this triggers backtracking } // END: Modified Sudoku Solver // START: Check if the grid is uniquely solvable void Sudoku::countSoln(int &number) { int row, col; if(!FindUnassignedLocation(this->grid, row, col)) { number++; return ; } for(int i=0;i<9 && number<2;i++) { if( isSafe(this->grid, row, col, this->guessNum[i]) ) { this->grid[row][col] = this->guessNum[i]; countSoln(number); } this->grid[row][col] = UNASSIGNED; } } // END: Check if the grid is uniquely solvable // START: Gneerate puzzle void Sudoku::genPuzzle() { for(int i=0;i<81;i++) { int x = (this->gridPos[i])/9; int y = (this->gridPos[i])%9; int temp = this->grid[x][y]; this->grid[x][y] = UNASSIGNED; // If now more than 1 solution , replace the removed cell back. int check=0; countSoln(check); if(check!=1) { this->grid[x][y] = temp; } } } // END: Generate puzzle // START: Printing into SVG file void Sudoku::printSVG(string path="") { string fileName = path + "svgHead.txt"; ifstream file1(fileName.c_str()); stringstream svgHead; svgHead << file1.rdbuf(); ofstream outFile("puzzle.svg"); outFile << svgHead.rdbuf(); for(int i=0;i<9;i++) { for(int j=0;j<9;j++) { if(this->grid[i][j]!=0) { int x = 50*j + 16; int y = 50*i + 35; stringstream text; text<<"<text x=\""<<x<<"\" y=\""<<y<<"\" style=\"font-weight:bold\" font-size=\"30px\">"<<this->grid[i][j]<<"</text>\n"; outFile << text.rdbuf(); } } } outFile << "<text x=\"50\" y=\"500\" style=\"font-weight:bold\" font-size=\"15px\">Difficulty Level (0 being easiest): " <<this->difficultyLevel<<"</text>\n"; outFile << "</svg>"; } // END: Printing into SVG file // START: Calculate branch difficulty score int Sudoku::branchDifficultyScore() { int emptyPositions = -1; int tempGrid[9][9]; int sum=0; for(int i=0;i<9;i++) { for(int j=0;j<9;j++) { tempGrid[i][j] = this->grid[i][j]; } } while(emptyPositions!=0) { vector<vector<int> > empty; for(int i=0;i<81;i++) { if(tempGrid[(int)(i/9)][(int)(i%9)] == 0) { vector<int> temp; temp.push_back(i); for(int num=1;num<=9;num++) { if(isSafe(tempGrid,i/9,i%9,num)) { temp.push_back(num); } } empty.push_back(temp); } } if(empty.size() == 0) { cout<<"Hello: "<<sum<<endl; return sum; } int minIndex = 0; int check = empty.size(); for(int i=0;i<check;i++) { if(empty[i].size() < empty[minIndex].size()) minIndex = i; } int branchFactor=empty[minIndex].size(); int rowIndex = empty[minIndex][0]/9; int colIndex = empty[minIndex][0]%9; tempGrid[rowIndex][colIndex] = this->solnGrid[rowIndex][colIndex]; sum = sum + ((branchFactor-2) * (branchFactor-2)) ; emptyPositions = empty.size() - 1; } return sum; } // END: Finish branch difficulty score // START: Calculate difficulty level of current grid void Sudoku::calculateDifficulty() { int B = branchDifficultyScore(); int emptyCells = 0; for(int i=0;i<9;i++) { for(int j=0;j<9;j++) { if(this->grid[i][j] == 0) emptyCells++; } } this->difficultyLevel = B*100 + emptyCells; } // END: calculating difficulty level // START: The main function int main(int argc, char const *argv[]) { // Initialising seed for random number generation srand(time(NULL)); // Creating an instance of Sudoku Sudoku *puzzle = new Sudoku(); // Creating a seed for puzzle generation puzzle->createSeed(); // Generating the puzzle puzzle->genPuzzle(); // Calculating difficulty of puzzle puzzle->calculateDifficulty(); // testing by printing the grid puzzle->printGrid(); // Printing the grid into SVG file string rem = "sudokuGen"; string path = argv[0]; path = path.substr(0,path.size() - rem.size()); puzzle->printSVG(path); cout<<"The above sudoku puzzle has been stored in puzzles.svg in current folder\n"; // freeing the memory delete puzzle; return 0; } // END: The main function |
Sudoku-Generator
A Sudoku puzzle generator written in C++.
Steps to Use:-
Requirements:
-> git
-> Latest version C++ compiler , (this program has been tested on g++ only)
Linux and MacOS
Type the follwing commands on your terminal (without the ‘$’)
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$ git clone https://github.com/vaithak/Sudoku-Generator $ cd Sudoku-Generator $ bash setup.sh |
Now restart the terminal and you are good to go
To run => enter $ sudokuGen from anywhere in the terminal
You can view the svg image generated in any Browser.
Example Puzzle generated from the program
FlowChart
