Solving sodoku

soduku.py

def solve_soduku(grid):
    i,j =0,0
    while(i<9):
        while(j<9):
            if(grid[i][j]==0):
                if try_fill_missing_recursively(grid,i,j)==False:
                    return False                
            j+=1
        j=0
        i+=1
    return True

#Supporting functions for main solver


def try_fill_missing_recursively(grid,i,j):
    for val in range(1,10):
        if check_valid(grid,i,j,val):
            grid[i][j]=val
            if(solve_soduku(grid)):
                return True
            else:
                grid[i][j]=0
    return False





#Supporting functions for Check Valid
def check_valid(grid, i, j, val):
    if (check_row_unique(grid,j,val)!=True):
        return False
    if(check_col_unique(grid,i,val)!=True):
        return False
    if(check_three_unique(grid,i,j,val)!=True):
        return False
    return True

def check_row_unique(grid,j,val):
    k = 0
    while k < 9:
        if grid[k][j] == val: #keep the col j constant
            return False
        k += 1
    return True
def check_col_unique(grid,i,val):
    k = 0
    while k < 9:
        if grid[i][k] == val: #keep the row i constant
            return False
        k += 1
    return True

def check_three_unique(grid,i,j,val):
    start_row = (i//3) * 3
    start_col = (j//3) * 3
    end_row = start_row + 3
    end_col = start_col + 3
    while(start_row< end_row):
        while(start_col< end_col):
            if(grid[start_row][start_col]==val):
                return False
            start_col+=1
        start_col= j //3 *3
        start_row+=1
    return True