Sudoku solver | Python Fiddle

import copy

print("SUDOKU SOLVER")
print("ENTER Sudoku line by line.")
print("Each line must have 9 numbers divided by whitespaces.")
print("For empty cells use 0 (zero)")
"""
sudoku_arr_in = []
for i in range(0,9):
    while True:
        #print("line #",i, ": ", end="")
        s = "line #"+str(i)+ ": "
        line = raw_input(s)
        print( line)
        try:
            num_line = [int(s) for s in line.split(" ")]
        except:
            continue
        if(len(num_line)==9):
            sudoku_arr_in.append(num_line)
            break
"""
sudoku_arr_in = [[3,0,0,6,0,0,0,0,0],
                 [0,0,0,0,1,0,0,4,0],
                 [0,0,0,0,0,0,0,2,0],
                 [0,2,0,0,0,0,0,8,0],
                 [0,0,0,5,0,0,7,0,0],
                 [0,0,8,3,0,0,0,0,0],
                 [1,4,0,0,2,0,0,0,0],
                 [5,0,0,0,0,0,6,0,0],
                 [0,0,0,0,0,0,3,0,0]]#MINIMAL

##                [[0,0,1,0,0,0,4,6,0],
##                 [9,0,0,0,5,7,0,0,0],
##                 [2,0,0,1,0,0,0,0,7],
##                 [0,2,0,8,0,3,6,0,0],
##                 [0,4,0,0,9,0,0,3,0],
##                 [0,0,3,7,0,4,0,5,0],
##                 [1,0,0,0,0,8,0,0,5],
##                 [0,0,0,5,3,0,0,0,2],
##                 [0,8,5,0,0,0,9,0,0]]#HARD
                 
##EASY
##                 [[0, 6, 0, 0, 0, 5, 0, 7, 0],
##                 [1,4,0,7,0,3,9,0,0],
##                 [0,0,7,8,0,0,5,4,0],
##                 [0,0,6,0,7,9,0,0,5],
##                 [3,5,0,0,0,0,0,1,7],
##                 [7,0,0,5,3,0,2,0,0],
##                 [0,2,8,0,0,6,7,0,0],
##                 [0,0,3,4,0,1,0,9,2],
##                 [0,9,0,2,0,0,0,8,0]]

sudoku_arr = copy.deepcopy(sudoku_arr_in)

def get_flat_sub_square_for(i,j):
    start_i = int(i/3)*3
    start_j = int(j/3)*3
    sub_square = [l[start_j:start_j+3] for l in sudoku_arr[start_i:start_i+3]]
    return [val for sublist in sub_square for val in sublist]

def get_column_for(c):
    return [line[c] for line in sudoku_arr]

def get_possibilities_for_line(dict_list,l):
    return [p for p in dict_list if p["line"]==l]

def get_possibilities_for_col(dict_list,l):
    return [p for p in dict_list if p["col"]==l]

def get_possibilities_for_sub_square(dict_list,p0):
    p0_square_no = get_sub_square_no(p0["line"],p0["col"])
    return [p for p in dict_list if get_sub_square_no(p["line"],p["col"])==p0_square_no]

def check_is_it_only_one_possibility(dict_list, a):
    count_a = 0;
    for d in dict_list:
        count_a += d["poss_list"].count(a)
    return count_a==1

def check_is_it_only_one_possibility_at_all(a):
    count_a = 0;
    for line in sudoku_arr:
        count_a += line.count(a)
    return count_a==8

def get_sub_square_no(x,y):
    return int(x/3)*3+int(y/3)

#create and fill list of possibilities
possibilities = []
for i in range(0,9):
    for j in range(0,9):
        if(sudoku_arr[i][j]==0):
            possibilities.append({"line":i, "col":j,
                                  "poss_list":[x for x in range(1,10)]})
#do search
iterations_without_changes=0
total_changes = 0
total_iterations = 0
print("total possibilities left:", len(possibilities))
while possibilities:# and iterations_without_changes<1000:
    total_iterations += 1
    for p in possibilities:
        #check is it only one possibility here
        if (len(p["poss_list"])==1):
           #print("appling changes at ", p["line"], p["col"])
           sudoku_arr[p["line"]][p["col"]]=p["poss_list"][0]
           possibilities.remove(p)
           iterations_without_changes=0
           total_changes+=1
        else:
           change_applied=False
           for x in p["poss_list"]:
               if(check_is_it_only_one_possibility_at_all(x)
                  or check_is_it_only_one_possibility(get_possibilities_for_line(possibilities,p["line"]),x)
                  or check_is_it_only_one_possibility(get_possibilities_for_col(possibilities,p["col"]),x)
                  or check_is_it_only_one_possibility(get_possibilities_for_sub_square(possibilities,p),x)):
                  #print("appling changes at ", p["line"], p["col"])
                  sudoku_arr[p["line"]][p["col"]]=x
                  #print("p:",p)
                  possibilities.remove(p)
                  iterations_without_changes=0
                  total_changes+=1
                  change_applied=True
                  break
           if(change_applied):
               continue
           #modify list of  possibilities:
           iterations_without_changes+=1
           #remove numbers in line
           for x in sudoku_arr[p["line"]]:
               if(x!=0) and (x in p["poss_list"]):
                   p["poss_list"].remove(x)
           #remove numbers in column
           for x in get_column_for(p["col"]):
               if(x!=0)and (x in p["poss_list"]):
                   p["poss_list"].remove(x)
           #remove numbers in sub-square
           for x in get_flat_sub_square_for(p["line"], p["col"]):
                if(x!=0)and (x in p["poss_list"]):
                    p["poss_list"].remove(x)

print("sudoku state:",sudoku_arr)
"""
print("possibilities left:", possibilities)
print("total possibilities left:", len(possibilities))
print("total changes:",total_changes)
print("total_iterations:",total_iterations)
print("iterations_without_changes:", iterations_without_changes)
"""

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