sudoku_validator.py

def notInRow(arr, row):  
  
    st = set()  
    for i in range(0, 9):  
        if arr[row][i] in st:  
            return False
        if arr[row][i] != 0:  
            st.add(arr[row][i])       
    return True
  
def notInCol(arr, col):  
  
    st = set()  
    for i in range(0, 9):  
        if arr[i][col] in st: 
            return False
        if arr[i][col] != 0:  
            st.add(arr[i][col])       
    return True
  
def notInBox(arr, startRow, startCol):  
  
    st = set()  
    for row in range(0, 3):  
        for col in range(0, 3):  
            curr = arr[row + startRow][col + startCol]  
            if curr in st:  
                return False
            if curr != 0:  
                st.add(curr)         
    return True

def isValid(arr, row, col):  
  
    return (notInRow(arr, row) and notInCol(arr, col) and
            notInBox(arr, row - row % 3, col - col % 3))  
  
def isValidConfig(arr):  
  
    for i in range(0, 9):  
        for j in range(0, 9):  
            if not isValid(arr, i, j):  
                return False   
    return True