Blank Sudoku Grid: Fill & Download for Free

The Backtracking Algorithm is a recursive algorithm that attempts to solve a given problem by testing all possible paths towards a solution until a valid solution is found. Every time a path is tested, in case a solution is not found, the algorithm backtracks to test another possible path and this procedure is repeated until a valid solution is found or all paths have been tested.In a nutshell, this is analogous to finding your way out of a maze. If the road ahead splits into let’s say 3 different paths, you start off by taking one path. You walk for a while a while and you reach a dead end, you backtrack your way to get back to where the road split into 3. Now that you know which of the 3 paths leads to a dead end, you choose an alternative path and if you again reach a dead end, you backtrack. This process is repeated until you reach the exit of the maze.Sudoku ProblemGiven a partially filled grid of size [math]9\times9[/math], completely fill the grid with numbers between [math]1[/math] and [math]9[/math].A fully filled grid is a solution if:Each row has all numbers form [math]1[/math] to [math]9[/math].Each column has all numbers form [math]1[/math] to [math]9[/math].Each sub-grid (if any) has all numbers form [math]1[/math] to [math]9[/math].Sudoku puzzles are commonly found in local newspapers and are a good exercise for the brain if solved logically.Now, to demonstrate the Backtracking Algorithm, I have written a small code in C++ language. In the main() function, you can edit the sudoku puzzle (line [math]88[/math]) to your desired sudoku problem. Note that in my code, a 0 in the sudoku grid array denotes a blank cell in the grid. So, feel free to experiment and play around with my code.Here’s the C++ code…#include <iostream>  using namespace std;  bool validity_check(int sudoku[9][9],int n,int p,int q) {  for(int i=0;i<9;i++)  {  if(sudoku[p][i]==n && q!=i)  {  return false;  }  }  for(int i=0;i<9;i++)  {  if(sudoku[i][q]==n && p!=i)  {  return false;  }  }  int bx=q/3;  int by=p/3;  for(int i=by*3;i<by*3+3;i++)  {  for(int j=bx*3;j<bx*3+3;j++)  {  if(sudoku[i][j]==n && i!=p && j!=q)  {  return false;  }  }  }  return true; }  int blank(int sudoku[9][9],int *r,int *c) {  for(*r=0;*r<9;(*r)++)  {  for(*c=0;*c<9;(*c)++)  {  if(sudoku[*r][*c]==0)  {  return 1;  }  }  }  return 0; }  bool solver(int sudoku[9][9]) {  int row=0,col=0;  int x=-1,y=-1;   if (!blank(sudoku, &row, &col)){  return 1;  }  for(int i=1;i<=9;i++)  {  if(validity_check(sudoku,i,row,col))  {  sudoku[row][col]=i;  if(solver(sudoku))  {  return true;  }  sudoku[row][col]=0;  }  }  return false; }  void print_sudoku(int sudoku[9][9]) {  for(int i=0;i<9;i++)  {  for(int j=0;j<9;j++)  {  cout<<sudoku[i][j]<<" ";  }  cout<<endl<<endl;  } }  int main() {  int sudoku[9][9] = {  {8, 0, 0, 0, 0, 0, 0, 0, 0},  {0, 0, 3, 6, 0, 0, 0, 0, 0},  {0, 7, 0, 0, 9, 0, 2, 0, 0},  {0, 5, 0, 0, 0, 7, 0, 0, 0},  {0, 0, 0, 0, 4, 5, 7, 0, 0},  {0, 0, 0, 1, 0, 0, 0, 3, 0},  {0, 0, 1, 0, 0, 0, 0, 6, 8},  {0, 0, 8, 5, 0, 0, 0, 1, 0},  {0, 9, 0, 0, 0, 0, 4, 0, 0}};   cout<<"-------------------------"<<endl;  if (solver(sudoku) == true)  {  cout<<" SOLVED! "<<endl;  cout<<"-------------------------"<<endl;  print_sudoku(sudoku);  }  else  cout << "Solution Does Not Exist!";  return 0; } If you google for the Toughest Sudoku Puzzle out there, you’ll most likely be shown this puzzle…So I tried feeding this puzzle as the input grid in my code and here’s the solution that I got…Peace!Link to my GitHub Repository - https://github.com/7enTropy7/Sudoku_Solver

Because if the sentence is uttered in context, and you already know what most of the keywords mean, the number of possible solutions is limited.E.g. If you asked where someone was, and hear “He [something something] bathroom [ending]”, that could only mean He is in the bathroom or He was in the bathroom or He might be in the bathroom or He was heading to the bathroom, but it certainly cannot mean He’s out fox hunting or Yoshi likes Mario or It is a truth universally acknowledged that a single man in possession of a good fortune must be in want of a wife.It’s like solving a partially-filled crossword or sudoku.When you are creating your own sentences, though, you have the equivalent of a completely blank sudoku grid, with no numbers already filled in.You can generate anything you want! Only some of it is going to sound wrong!You have an infinite number of sentences you can utter — even if some of them don’t fit the context, that’s called changing the topic of conversation. You have to build your sentences from nothing, rather than mentally fill in the partially assembled sentences provided.And so the process is quite different.

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