created 36_Valid_Sudoku

Python/36_Valid_Sudoku.py

@@ -0,0 +1,53 @@
+# Problem Link:    https://leetcode.com/problems/valid-sudoku/
+# 36. Valid Sudoku
+
+'''
+Problem statement:
+    Determine if a 9 x 9 Sudoku board is valid. Only the filled cells need to be validated according to the following rules:
+        Each row must contain the digits 1-9 without repetition.
+        Each column must contain the digits 1-9 without repetition.
+        Each of the nine 3 x 3 sub-boxes of the grid must contain the digits 1-9 without repetition.
+'''
+
+'''
+Example:
+    Input:
+        [["5","3",".",".","7",".",".",".","."]
+        ,["6",".",".","1","9","5",".",".","."]
+        ,[".","9","8",".",".",".",".","6","."]
+        ,["8",".",".",".","6",".",".",".","3"]
+        ,["4",".",".","8",".","3",".",".","1"]
+        ,["7",".",".",".","2",".",".",".","6"]
+        ,[".","6",".",".",".",".","2","8","."]
+        ,[".",".",".","4","1","9",".",".","5"]
+        ,[".",".",".",".","8",".",".","7","9"]]
+    Output:
+        True
+'''
+class Solution:
+    def isValidSudoku(self, board):
+        # First check if any number is repeated in same row or column.
+        for i in range(len(board)):
+            for j in range(len(board)):
+                if board[i][j]==".":
+                    continue
+                if board[i].count(board[i][j])>1:   #check for row
+                    return False
+                c=0
+                for k in range(len(board)):
+                    if board[k][j]==board[i][j]:    #check for column
+                        c+=1
+                if c>1:
+                    return False    
+        # Now check for sinlge-single 3x3 matrix if it contain all different elemnts or not 
+        for i in range(0,len(board),3):
+            for j in range(0,len(board),3):
+                nums = [0]*10
+                for ii in range(i,i+3):
+                    for jj in range(j,j+3):
+                        if board[ii][jj] != '.': 
+                            if nums[int(board[ii][jj])] <1:
+                                nums[int(board[ii][jj])] = int(board[ii][jj])
+                            else:
+                                return False
+        return True