Merge pull request #327 from Tejas1510/sudoku

A sudoku Solver

Author: tejan-singh

Python/SudokuSolver/Readme.MD

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+# Sudoku Solver
+
+## Introduction
+```
+This is a python application which takes a matrix as input and gives the solved sudoku problem as the output.
+It is based on the backtracking algorithm.
+```
+## How to use it :
+1. Download or clone the repository
+2. Install Required Libraries
+3. Run sudoku.py
+5. you will be asked to give enter the complete sudoku as a matrix
+6. you will get the the solved sudoku as the input
+
+## Output
+
+![endpoint](https://github.com/Tejas1510/hacking-tools-scripts/blob/sudoku/Python/SudokuSolver/images/image1.png)
+
+![endpoint](https://github.com/Tejas1510/hacking-tools-scripts/blob/sudoku/Python/SudokuSolver/images/image2.png)
+
+![built with love](https://forthebadge.com/images/badges/built-with-love.svg)
+
+Check out my Github profile [Tejas1510!](https://github.com/Tejas1510)

Python/SudokuSolver/images/image1.png

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+#Take Matrix as input
+n=int(input(" Enter no of rows and columns of sudoku problem : "))
+print("Please enter a ",n,"x",n,"Matrix")
+matrix = [[0 for i in range(n)] for j in range(n)]
+for i in range(0,n):
+    for j in range(0,n):
+        matrix[i][j] = int(input())
+# solve matrix which bascially uses two function find_empty() and valid()
+def solve(matrix):
+    find = find_empty(matrix)
+    # if value of find is false
+    if not find:
+        return True
+    else:
+        row, col = find
+    # looping through all rows of matrix
+    for i in range(1,n+1):
+        if valid(matrix, i, (row, col)):
+            matrix[row][col] = i
+
+            if solve(matrix):
+                return True
+
+            matrix[row][col] = 0
+    return False
+def valid(matrix, num, pos):
+    # Check row
+    for i in range(len(matrix[0])):
+        if matrix[pos[0]][i] == num and pos[1] != i:
+            return False
+    # Check column
+    for i in range(len(matrix)):
+        if matrix[i][pos[1]] == num and pos[0] != i:
+            return False
+    # Check box
+    box_x = pos[1] // 3
+    box_y = pos[0] // 3
+    #looping over the complete matrix
+    for i in range(box_y*3, box_y*3 + 3):
+        for j in range(box_x * 3, box_x*3 + 3):
+            if matrix[i][j] == num and (i,j) != pos:
+                return False
+    return True
+#function to print the complete sudoku
+def print_board(matrix):
+    for i in range(len(matrix)):
+        if i % 3 == 0 and i != 0:
+            print("- - - - - - - - - - - - - ")
+
+        for j in range(len(matrix[0])):
+            if j % 3 == 0 and j != 0:
+                print(" | ", end="")
+
+            if j == 8:
+                print(matrix[i][j])
+            else:
+                print(str(matrix[i][j]) + " ", end="")
+# function to find whether entered matrix is empty or not
+def find_empty(matrix):
+    for i in range(len(matrix)):
+        for j in range(len(matrix[0])):
+            if matrix[i][j] == 0:
+                return (i, j)  # row, col
+    return None
+print("The entered Matrix for sudoku solver is : ")
+print("")
+print_board(matrix)
+solve(matrix)
+print("")
+print("***********************************************")
+print("")
+print("The output is : ")
+print("")
+print_board(matrix)