I'm trying to do the polish notation challenge on kattis.com. Thing is, I feel I have done everything they asked for and I've tried fixing everything I could think of. I even looked up some other's solutions and while theirs are more clean I want to continue on mine as I am learning.
Why is it that for example this person's code works but not mine?
Here is my current code:
import sys
case = 1
valid_ints = set([str(i) for i in range(-10,11)])
def simplify(index, myLine, processed):
while index+1 > 0:
if (myLine[index] == "+" or myLine[index] == "-" or myLine[index] == "*") and index < len(myLine)-2:
if myLine[index+1] in valid_ints and myLine[index+2] in valid_ints:
try:
processed = myLine[index+3:] + processed
a = str(myLine[index+1] + myLine[index] + myLine[index+2])
processed.insert(0, str(eval(a)))
del myLine[index:]
except:
processed = [myLine[index], myLine[index+1], myLine[index+2]] + processed
del myLine[index:]
elif len(myLine) < 3:
processed = myLine + processed
del myLine[index]
index -= 1
processed = myLine + processed
return processed
for line in sys.stdin:
myLine = line.split()
processed = []
index = len(myLine)-1
savedprocessed = []
processed = simplify(index, myLine, processed)
while True:
if savedprocessed == processed:
break
else:
savedprocessed = []
savedprocessed += processed
processed = simplify(len(processed)-1, processed, [])
result = " ".join(savedprocessed)
print("Case " + str(case) + ": " + result)
case += 1
if case > 5:
break
You're bringing some other language style to Python, that's unnecessary because Python is more flexible.
I've simplified as much as I can here.
Split the input string on white spaces and iterate over the tokens.
For every operator in the expression, push a list onto the stack and append the operator and its operands to the list.
Now pop each list off the stack and process the list
def simplify(exp):
stack1 = []
ops = set('+*-')
for token in exp.split():
if token in ops:
stack1.append([])
stack1[-1].append(token)
stack2 = []
while stack1:
top = stack1.pop()
while len(top) < 3 and stack2:
top.append(stack2.pop())
if any(x.isalpha() for x in top):
simplified = ' '.join(top)
else:
top[0], top[1] = top[1], top[0]
simplified = str(eval(''.join(top)))
stack2.append(simplified)
return simplified
exp = '* - 6 + x -6 - - 9 6 * 0 c'
print(exp)
simplify(exp)
Output;
* - 6 + x -6 - - 9 6 * 0 c
* - 6 + x -6 - - 3 * 0 c
Related
I'm currently learning Python and I'm stuck on this specific question.
Image
Here is my current code:
word = input()
text = 0
wordch = 0
positions = 0
repeated = 0
while repeated != 2:
for i in range(0, len(tablet)):
if tablet[i] == word[wordch]:
text += 1
wordch += 1
if text == len(word):
positions += 1
text = 0
wordch = 0
elif repeated == 1 and text == len(word):
positions += 1
text = 0
wordch = 0
break
elif i == len(tablet)-1:
repeated += 1
break
elif tablet[i] != word[wordch]:
text == 0
wordch == 0
print(positions)
I would hope for a code that is really basic using the same concepts but please do answer.
Thank you!
I have tried to solve the problem by using a different approach. As we know that we can only use (len(fav_word)) - 1 letters if we tried to create the substring in a cyclic manner from the end since if we took any more characters, we would have created them from the start itself without the cycle.
So, I just created a new string from the original string by appending the starting (len(fav_word)) - 1 to the original string and then find all occurrences of the fav_string in the new string.
def find_all(a_str, sub):
start = 0
while True:
start = a_str.find(sub, start)
if start == -1: return
yield start
start += 1
x = "cabccabcab"
fav = "abc"
y = x + x[0:len(fav)-1]
print(len(list(find_all(y, fav)))) # Output: 3
x = "ababa"
fav = "aba"
y = x + x[0:len(fav)-1]
print(len(list(find_all(y, fav)))) # Output: 2
x = "aaaaaa"
fav = "aa"
y = x + x[0:len(fav)-1]
print(len(list(find_all(y, fav)))) # Output: 6
x = "abaaba"
fav = "aaba"
y = x + x[0:len(fav)-1]
print(len(list(find_all(y, fav)))) # Output: 2
def find_str(g,find):
lg = len(g)
lf = len(find)
x=0
s=""
for index, i in enumerate(g):
if i == find[0]:
if index+lf <= lg:
s = "".join(g[index:index+lf])
if s == find:
x+=1
else:
rem = "".join(g[index:])
lr = len(rem)
for index,i in enumerate(g):
rem+=i
lr+=1
if lr == lf:
if rem == find:
x+=1
break
return x
print(find_str("abaaba","aaba"))
def split(word):
return [char for char in word]
x = "aaaaaa"
pattern = "aa"
mylist=split(x)
ok=True
occurrences=0
buffer=""
while ok:
char=mylist.pop(0)
buffer+=char
if buffer==pattern:
occurrences+=1
buffer=""
if len(mylist)==0:
ok=False
print(occurrences)
output:3
def binarySearch(list, selection):
start = 0
end = len(list) - 1
while start <= end:
middle = start + (end - start) // 2
middleValue = list[middle]
if middleValue == selection:
return middle
elif selection < middleValue:
end = middle - 1
else:
start = middle + 1
return None
lista = [1, 5, 7, 10, 11, 19,]
print(lista)
selectiona = int(input('Enter a number to search for: '))
index = lista.index(selectiona)
binarySearch(lista, selectiona)
print(str(selectiona)) + "found at index " + str(index))
exit = input()
It works without printing the index, but this is a requirement. If anyone can advise me on what I'm doing wrong I'd be greatly appreciative. thanks
In the line print(str(selectiona)) + "found at index " + str(index)) your parentheses are wrong, you close one too many after selectiona. Try this instead:
print(str(selectiona) + "found at index " + str(index))
Additionally, the result of your binary search isn't what you're printing. Did you mean to do index = binarySearch(lista, selectiona) instead?
You are fetching the index using python modules in the line index = lista.index(selectiona) and you are not using the output provides by the binarySearch function.
def binarySearch(list, selection):
start = 0
end = len(list) - 1
while start <= end:
middle = start + (end - start) / 2
middleValue = list[middle]
if middleValue == selection:
return middle
elif selection < middleValue:
end = middle - 1
else:
start = middle + 1
return None
lista = [1, 5, 7, 10, 11, 19,]
print(lista)
selectiona = int(input('Enter a number to search for: '))
index = binarySearch(lista, selectiona)
if index:
print(str(selectiona) + " found at index " + str(index))
else:
print(str(selectiona) + " is not there in the list")
exit = input()
I have the following code that is self explanatory in the docstring. How do I get it to not flag single letters with a 1, thereby turning a single digit into 2 in the final compressed string?
For example in the docstring it turns AAABBBBCDDDD -> A3B4C1D4 but I want it to turn into A3B4CD4. I'm new at this so it's any comments are greatly appreciated.
class StringCompression(object):
'''
Run Length Compression Algorithm: Given a string of letters, such as
nucleotide sequences, compress it using numbers to flag contiguous repeats.
Ex: AAABBBBCDDDD -> A3B4C1D4
>>>x = StringCompression('AAAAbC')
>>>x.compress()
'A4bC'
'''
def __init__(self, string):
self.string = string
def compress(self):
'''Executes compression on the object.'''
run = ''
length = len(self.string)
if length == 0:
return ''
if length == 1:
return self.string #+ '1'
last = self.string[0]
count = 1
i = 1
while i < length:
if self.string[i] == self.string[i - 1]:
count += 1
else:
run = run + self.string[i - 1] + str(count)
count = 1
i += 1
run = (run + self.string[i - 1] + str(count))
return run
Here's an alternative solution using itertools.groupby and a generator:
from itertools import chain, groupby
x = 'AAABBBBCDDDD'
def compressor(s):
for i, j in groupby(s):
size = len(list(j))
yield (i, '' if size==1 else str(size))
res = ''.join(chain.from_iterable(compressor(x)))
print(res)
A3B4CD4
Now it works the way I wanted it to. Thanks!
class StringCompression(object):
'''
Run Length Compression Algorithm: Given a string of letters, such as
nucleotide sequences, compress it using numbers to flag contiguous repeats.
Ex: AAABBBBCDDDD -> A3B4CD4
Notice that single letter do not get a 1 flag to prevent expansion.
>>>x = StringCompression('AAAAbC')
>>>x.compress()
'A4bC'
'''
def __init__(self, string):
self.string = string
def compress(self):
'''Executes compression on the object.'''
run = ''
length = len(self.string)
if length == 0:
return ''
if length == 1:
return self.string #+ '1'
last = self.string[0]
count = 1
i = 1
while i < length:
if self.string[i] == self.string[i - 1]:
count += 1
else:
run = run + self.string[i - 1] + str(count)
count = 1
i += 1
run = (run + self.string[i - 1] + str(count))
compressed_string = ''
for i in run:
if i != '1':
compressed_string += i
return compressed_string
I'm having some formatting issues with my call to print function. For lack of knowledge of better ways to format, i've ended up with an issue. here is what it should look like
However the actual result of my print returns this.
def tupleMaker(inputString):
s1 = inputString.split()
# Adding the surname at the end of the string
s2 = [s1[len(s1) - 1]]
# Number of other names(no surname)
global noOfNames
noOfNames = len(s1) - 4
# Adding all the other names
for i in range(noOfNames):
s2.append((s1[i + 3]))
# Adding the Reg number
s2.append(s1[0])
# Adding the Degree scheme
s2.append(s1[2])
# Adding the year
s2.append("Year " + s1[1])
# Making it a tuple
t = ()
for i in range(len(s2)):
t = t + (s2[i],)
return t
def formatting(t):
s1 = ""
for i in range(len(t)):
s1 += t[i]
if (i == 0):
s1 += ", "
elif (i == len(t) - 4):
s1 += " "
else:
s1 += " "
#print(t[0] + ", ", end="")
#for i in range(noOfNames):
#print (t[i+1], end= " ")
#print(format(t[1+noOfNames], "<32s"))
#print(format(thenames, "<32d") + format(regNo, "<7d") + format(degScheme, ">6s") + format(year, ">1s")
print("")
print(s1)
I would recommend looking at using pythons built in string.format() function a small tutorial is located here: https://pyformat.info/
I am fairly new to python, I am not sure on how to fix a index string out of range. it happens right after the while loop when I want to send mylist[i][0] to formatting function. Any pointer on my code in general would be awesome!
def formatting(str1):
if str1 == '?':
return True
else:
return False
while(i <= len(mylist)):
val = formatting(mylist[i][0])
if val == True:
str1 = mylist[i]
str2 = mylist[i+1]
i = i + 2
format_set(str1, str2)
else:
if format == True:
if (margin + count + len(mylist[i])) <= width:
if (i == (len(mylist)-1)):
list2.append(mylist[i])
print(" " * margin + " ".join(list2))
break
list2.append(mylist[i])
count += len(mylist[i])
i += 1
else:
print(" " * margin + " ".join(list2))
list2 = []
count = 0
else:
temp_margin = margin
temp_width = width
width = 60
margin = 0
if (margin + count + len(mylist[i])) <= width:
if (i == (len(mylist)-1)):
list2.append(mylist[i])
print(" " * margin + " ".join(list2))
margin = temp_margin
width = temp_width
break
list2.append(mylist[i])
count += len(mylist[i])
i += 1
else:
print(" " * margin + " ".join(list2))
list2 = []
count = 0
change
i <= len(mylist)
to
i < len(mylist)
In the last iteration of the while loop, i is referring to the last value. Hence,
str2 = mylist[i+1]
is trying to reference a string outside the allowed range and you get an error.
EDIT: Also, as Wcrousse mentioned, the while (i <= len(...)) should be changed to i < len(...) because indexes go from 0 - (length-1).