Following are two different dynamic programming codes for fibonacci series. I cannot figure out the time complexity of these. Results of both are the same. Any help is appreciated.
#Code 1
def fibo(n) :
if mem[n] is not None:
return mem[n]
if n == 1 or n == 2 :
res = 1
else :
res = fibo(n - 1) + fibo(n - 2)
mem[n] = res
return res
n = int(input("Enter position :"))
mem = [None] * (n + 1)
fibo(n)
Code 2
def fibo(n) :
if len(mem) == n-1 :
return mem[n-1]
if n == 1 or n == 2 :
res = 1
else :
res = fibo(n - 1) + fibo(n - 2)
mem.append(res)
return res
n = int(input("Enter position :"))
mem = []
fibo(n)
Related
Here's my code:
def ispalindrome(p):
temp = p
rev = 0
while temp != 0:
rev = (rev * 10) + (temp % 10)
temp = temp // 10
if num == rev:
return True
else:
return False
num = int(input("Enter a number: "))
i = 1
count = 0
sum = 0
while (count <= num - 1):
if (palindrome(i) == True):
sum = sum + i
count = count + 1
i = i + 1
print("Sum of first", num, "palindromes is", sum)
I believe my ispalindrome() function works. I'm trying to figure out what's wrong inside my while loop.
here's my output so far:
n = 1 answer = 1,
n = 2 answer = 22,
n = 3 answer = 333 ...
I also think the runtime on this really sucks
Please help
i belive the problem is with your ispalindrom functon it returns 200 as palindrome number
def ispalindrome(p):
rev = int(str(p)[::-1])
if p == rev:
return True
else:
return False
num = int(input("Enter a number: "))
i = 1
count = 0
sum = 0
while (count <= num - 1):
if (ispalindrome(i) == True):
print(i)
sum = sum + i
count = count + 1
i = i + 1
print("Sum of first", num, "palindromes is", sum)
def is_palindrome(number):
return str(number) == str(number)[::-1]
num = int(input("Enter a number: "))
palindromes = [i for i in range(1, num) if is_palindrome(i)]
print(f"Sum of the {len(palindromes)} palindromes in range {num} is {sum(palindromes)}")
Basically my brain is not working right now can't figure out the best way to resolve this error. builtins.NameError: name 'numIters' is not defined
I know this problem is that numIters is not defined in its scope but don't know the best solution to fix that.
Here is the bulk of my code
import random
alg = int(input("Select the sorting algorithm \n 1 - linear search \n 2 - binary search \nEnter Choice: "))
n = int(input("Choose the size of the list: "))
def main():
createList(n,alg)
print(runTest(values,n,alg))
printResults(alg,n,numIters)
#print(linearSearch(values,2))
#print(binarySearch(values, 2))
def createList(n,alg):
global values
values = []
random.seed(1456)
for j in range(n):
values.append(random.randint(0, 2*n))
while len(values) == n:
if alg == 2:
values.sort()
print(values)
return values
elif alg == 1:
print(values)
return values
def linearSearch(values, target):
numIters = 0
for i in range(len(values)):
numIters = numIters + 1
if values[i] == target:
return numIters
return -1
def binarySearch(values, target):
numIters = 0
start = 0
high = len(values) - 1
while start <= high:
middle = (start + high)//2
if values[middle] == target:
numIters = numIters + 1
return numIters
elif values[middle] > target:
numIters = numIters + 1
high = middle - 1
else:
numIters = numIters + 1
start = middle + 1
return -1
def runTest(values,n,alg):
if alg == 2:
count = 0
for j in range(n * 2):
count = count + 1
tgt = random.randint(0, 2*n)
binarySearch(values, tgt)
return count
elif alg == 1:
count = 0
for j in range(n * 2):
count = count + 1
tgt = random.randint(0, 2*n)
linearSearch(values, tgt)
return count
def printResults(alg, n, numIters):
avgIter = n / numIters
if alg == 2:
algType = Binary
if alg == 1:
algType = Linear
print("Results \n n = %d \n %s = %f.2 " % (n,algtype,avgIter))
main()
Thank you in advance for any help given as I am still trying to learn and understand how python works as a whole.
You need to return numIters so that you can pass it to the next function. It looks like it currently gets returned from binarySearch and linearSearch to runTest, but it gets discarded there; just bubble it up like this (I'm going to add type annotations and comments to help me keep track of what's going on):
from typing import List, Tuple
def runTest(values: List[int], n: int, alg: int) -> Tuple[int, int]:
"""Returns count, numIters"""
numIters = 0 # default value in case n is so small we don't iterate
if alg == 2:
count = 0
for j in range(n * 2):
count = count + 1
tgt = random.randint(0, 2*n)
numIters = binarySearch(values, tgt)
return count, numIters
elif alg == 1:
count = 0
for j in range(n * 2):
count = count + 1
tgt = random.randint(0, 2*n)
numIters = linearSearch(values, tgt)
return count, numIters
raise ValueError("alg needs to be 1 or 2!")
Now in your main() you can do:
def main():
createList(n, alg)
count, numIters = runTest(values, n, alg)
print(count)
printResults(alg, n, numIters)
I tried making this code and run it, but the result showed "None".
I've edited by adding another else in the loop function, then it actually produces a int result of '57' which is not exactly the answer.
def double(n):
return n*2
def halve(n):
return n//2
def mult(m,n):
def loop(m,n):
if n>1:
if n%2 != 0:
return m + loop(double(m),halve(n))
else:
return m #added another else
else:
return m
if n>0:
return loop(m,n)
else:
return 0
print(mult(57,86))
by simple recursion
def double(n):
return n * 2
def halve(n):
return n // 2
def mult(m, n, a = 0):
if n % 2 != 0:
a = a + m
m = double(m)
n = halve(n)
if n % 2 == 0:
m = double(m)
n = halve(n)
if n != 0:
return mult(m, n, a)
return a
print(mult(57, 86))
by nested function
def double(n):
return n * 2
def halve(n):
return n // 2
def mult(m, n):
def loop(m, n, a = 0):
if n % 2 != 0:
a = a + m
m = double(m)
n = halve(n)
if n % 2 == 0:
m = double(m)
n = halve(n)
if n != 0:
return loop(m, n, a)
return a
return loop(m, n)
print(mult(57, 86))
If I have 2 numbers in binary form as a string, and I want to add them I will do it digit by digit, from the right most end. So 001 + 010 = 011
But suppose I have to do 001+001, how should I create a code to figure out how to take carry over responses?
bin and int are very useful here:
a = '001'
b = '011'
c = bin(int(a,2) + int(b,2))
# 0b100
int allows you to specify what base the first argument is in when converting from a string (in this case two), and bin converts a number back to a binary string.
This accepts an arbitrary number or arguments:
>>> def bin_add(*bin_nums: str) -> str:
... return bin(sum(int(x, 2) for x in bin_nums))[2:]
...
>>> x = bin_add('1', '10', '100')
>>> x
'111'
>>> int(x, base = 2)
7
Here's an easy to understand version
def binAdd(s1, s2):
if not s1 or not s2:
return ''
maxlen = max(len(s1), len(s2))
s1 = s1.zfill(maxlen)
s2 = s2.zfill(maxlen)
result = ''
carry = 0
i = maxlen - 1
while(i >= 0):
s = int(s1[i]) + int(s2[i])
if s == 2: #1+1
if carry == 0:
carry = 1
result = "%s%s" % (result, '0')
else:
result = "%s%s" % (result, '1')
elif s == 1: # 1+0
if carry == 1:
result = "%s%s" % (result, '0')
else:
result = "%s%s" % (result, '1')
else: # 0+0
if carry == 1:
result = "%s%s" % (result, '1')
carry = 0
else:
result = "%s%s" % (result, '0')
i = i - 1;
if carry>0:
result = "%s%s" % (result, '1')
return result[::-1]
Can be simple if you parse the strings by int (shown in the other answer). Here is a kindergarten-school-math way:
>>> def add(x,y):
maxlen = max(len(x), len(y))
#Normalize lengths
x = x.zfill(maxlen)
y = y.zfill(maxlen)
result = ''
carry = 0
for i in range(maxlen-1, -1, -1):
r = carry
r += 1 if x[i] == '1' else 0
r += 1 if y[i] == '1' else 0
# r can be 0,1,2,3 (carry + x[i] + y[i])
# and among these, for r==1 and r==3 you will have result bit = 1
# for r==2 and r==3 you will have carry = 1
result = ('1' if r % 2 == 1 else '0') + result
carry = 0 if r < 2 else 1
if carry !=0 : result = '1' + result
return result.zfill(maxlen)
>>> add('1','111')
'1000'
>>> add('111','111')
'1110'
>>> add('111','1000')
'1111'
It works both ways
# as strings
a = "0b001"
b = "0b010"
c = bin(int(a, 2) + int(b, 2))
# as binary numbers
a = 0b001
b = 0b010
c = bin(a + b)
you can use this function I did:
def addBinary(self, a, b):
"""
:type a: str
:type b: str
:rtype: str
"""
#a = int('10110', 2) #(0*2** 0)+(1*2**1)+(1*2**2)+(0*2**3)+(1*2**4) = 22
#b = int('1011', 2) #(1*2** 0)+(1*2**1)+(0*2**2)+(1*2**3) = 11
sum = int(a, 2) + int(b, 2)
if sum == 0: return "0"
out = []
while sum > 0:
res = int(sum) % 2
out.insert(0, str(res))
sum = sum/2
return ''.join(out)
def addBinary(self, A, B):
min_len, res, carry, i, j = min(len(A), len(B)), '', 0, len(A) - 1, len(B) - 1
while i>=0 and j>=0:
r = carry
r += 1 if A[i] == '1' else 0
r += 1 if B[j] == '1' else 0
res = ('1' if r % 2 == 1 else '0') + res
carry = 0 if r < 2 else 1
i -= 1
j -= 1
while i>=0:
r = carry
r += 1 if A[i] == '1' else 0
res = ('1' if r % 2 == 1 else '0') + res
carry = 0 if r < 2 else 1
i -= 1
while j>=0:
r = carry
r += 1 if B[j] == '1' else 0
res = ('1' if r % 2 == 1 else '0') + res
carry = 0 if r < 2 else 1
j -= 1
if carry == 1:
return '1' + res
return res
#addition of two binary string without using 'bin' inbuilt function
numb1 = input('enter the 1st binary number')
numb2 = input("enter the 2nd binary number")
list1 = []
carry = '0'
maxlen = max(len(numb1), len(numb2))
x = numb1.zfill(maxlen)
y = numb2.zfill(maxlen)
for j in range(maxlen-1,-1,-1):
d1 = x[j]
d2 = y[j]
if d1 == '0' and d2 =='0' and carry =='0':
list1.append('0')
carry = '0'
elif d1 == '1' and d2 =='1' and carry =='1':
list1.append('1')
carry = '1'
elif (d1 == '1' and d2 =='0' and carry =='0') or (d1 == '0' and d2 =='1' and
carry =='0') or (d1 == '0' and d2 =='0' and carry =='1'):
list1.append('1')
carry = '0'
elif d1 == '1' and d2 =='1' and carry =='0':
list1.append('0')
carry = '1'
else:
list1.append('0')
if carry == '1':
list1.append('1')
addition = ''.join(list1[::-1])
print(addition)
Not an optimal solution but a working one without use of any inbuilt functions.
# two approaches
# first - binary to decimal conversion, add and then decimal to binary conversion
# second - binary addition normally
# binary addition - optimal approach
# rules
# 1 + 0 = 1
# 1 + 1 = 0 (carry - 1)
# 1 + 1 + 1(carry) = 1 (carry -1)
aa = a
bb = b
len_a = len(aa)
len_b = len(bb)
min_len = min(len_a, len_b)
carry = 0
arr = []
while min_len > 0:
last_digit_aa = int(aa[len(aa)-1])
last_digit_bb = int(bb[len(bb)-1])
add_digits = last_digit_aa + last_digit_bb + carry
carry = 0
if add_digits == 2:
add_digits = 0
carry = 1
if add_digits == 3:
add_digits = 1
carry = 1
arr.append(add_digits) # will rev this at the very end for output
aa = aa[:-1]
bb = bb[:-1]
min_len -= 1
a_len_after = len(aa)
b_len_after = len(bb)
if a_len_after > 0:
while a_len_after > 0:
while carry == 1:
if len(aa) > 0:
sum_digit = int(aa[len(aa) - 1]) + carry
if sum_digit == 2:
sum_digit = 0
carry = 1
arr.append(sum_digit)
aa = aa[:-1]
else:
carry = 0
arr.append(sum_digit)
aa = aa[:-1]
else:
arr.append(carry)
carry = 0
if carry == 0 and len(aa) > 0:
arr.append(aa[len(aa) - 1])
aa = aa[:-1]
a_len_after -= 1
if b_len_after > 0:
while b_len_after > 0:
while carry == 1:
if len(bb) > 0:
sum_digit = int(bb[len(bb) - 1]) + carry
if sum_digit == 2:
sum_digit = 0
carry = 1
arr.append(sum_digit)
bb = bb[:-1]
else:
carry = 0
arr.append(sum_digit)
bb = bb[:-1]
else:
arr.append(carry)
carry = 0
if carry == 0 and len(bb) > 0:
arr.append(bb[len(bb) - 1])
bb = bb[:-1]
b_len_after -= 1
if carry == 1:
arr.append(carry)
out_arr = reversed(arr)
out_str = "".join(str(x) for x in out_arr)
return out_str
I am making some practice code for a game similar to the board game, MasterMind-- and It keeps coming out with this error, and I can't figure out why it's doin it. Here's the code:
def Guess_Almost (Guess, Answer):
a = ''.join([str(v) for v in Answer])
g = str(Guess)
n = 0
am = 0
while n < 5:
if g[n] == a[0]:
am = am + 1
if g[n] == a[2]:
am = am + 1
if g[n] == a[3]:
am = am + 1
if g[n] == a[3]:
am = am + 1
n = n + 1
return(am)
Okay, the Guess is specified to be 4 integers, and the Answer is a list containing 4 numbers. They both have the same 'len' after the code, so i don't have a clue.
The point of this code is to turn the Answer into a string of 4 numbers, and see if any of those numbers match thoise of the guess, and return how many total matches there are.
See if this helps
def Guess_Almost (Guess, Answer):
a = ''.join([str(v) for v in Answer])
g = str(Guess)
n = 0
am = 0
if len(g) >= 5 and len(a) >=4:
while n < 5:
if g[n] == a[0]:
am = am + 1
if g[n] == a[2]:
am = am + 1
if g[n] == a[3]:
am = am + 1
if g[n] == a[3]:
am = am + 1
n = n + 1
return(am)