Skip to main content

/docs/images/banner.jpg

Python

Day Two

List Basics​

l = ["Tejas", "A", "b", "c", 98, 78.34, "hello"]
print(l)
print(type(l))
print(l[0])
print(l[1])
print(l[-1])
print(l[-2])
print(l[:3])
print(l[3:])
print(l[2:5:2])
l[0] = "HELLO"
print(l[0])
l.append("Appended")
print(l)
l.insert(2, "hhelo")
l.insert(5, 3)
print(l)
l.remove("HELLO")
print(l)
cplist = l.copy()
print(cplist)
tl = [[1, 2, 3], ["a", "b", "c"]]
r = 0
c = 2
print(tl[r][c])

l1 = ["secret", "santa"]
print(l1*2)
l2 = [1, 2]
print(l1+l2)
del l1
l2.clear
print(l2)

myname = list("Tejas")
print(myname)

unsorted_list = [1,2,4,2,34,32,1]
unsorted_list.sort(reverse=True)
print(unsorted_list)

oglist = [12,34,56]
pointingList = oglist
print(id(oglist))
print(id(pointingList))

# char ops
print('Sej@123'.isalnum())
print('JohnDoe'.isalpha())
print('899'.isdigit())
print("".islower())
print("hello world".isspace())
print(" ".isspace())

l = [1,2,3,4,4,4]
l.count(4)

Problems

Maximum Element​

list = [ 3,3,4,2,4,4,2,4,4]
min,max=0,0
for i in list:
    if i in dict:
        dict[i] += 1
    else:
        dict[i] = 1
print(dict)
max = -1
for i,j in dict.items():
    if j > max:
        max = j
        max_key = i
print(max_key)

Other method​

list = [ 3,3,4,2,4,4,2,4,4]
min,max=list[0],list[0]
maxIdx,minIdx=0,0
for i in range(len(list)):
if max > list[i]:
max = list[i]
maxIdx=i
if min < list[i]:
min=list[i]
minIdx=i
print("Max",maxIdx,"VALUE",max)
print("Min",minIdx,"VALUE",min)

Move Zeros from List to End​


list = [0,0,34,4,4,5,5]
len_list  = len(list)
new_list=[]
for i in list:
    if (i!=0):
        new_list.append(i)
for i in range(0,(len_list-len(new_list))):
    new_list.append(0)
print(new_list)

Kth maximum element​

list = [3,2,1,5,6,4]
k=2
# list.sort()
# print(list)
# k=2
# print(list[len(list)-k])

def find_max(list):
    max=list[0]
    for i in range(len(list)):
        if max < list[i]:
            max = list[i]
    # print(max)
    return max


for i in range(k):
    max=find_max(list)
    list.remove(max)

print(list)
print(find_max(list))

Conditional List iterations​

budget =500
cart = [10,100,200,600,400]
for itm in cart:
    if itm>budget:
        print("Not sufficient budget")
        continue
    print(itm)
else:
    print("u purchased everything")

Check if input is number, alphabet or space​

x= input()
if(x.isdigit()):
    print("Digit")
if(x.isalpha()):
    print("Alphabet")
if(x.isspace()):
    print("Space")

Common Elements in two lists​

lista = [ 1,2,3,4]
listb = [3,4,5,6]
lista.sort()
listb.sort()
listc=[]

for j in listb:
    if j in lista:
        print(j)
        listc.append(j)
    else:
        break
print(listc)

First Non repeating character​

list = [1,2,3,5,2,1]
dict={}
for i in list:
    if i in dict:
        dict[i] += 1
    else:
        dict[i] = 1
print(dict)

for i in list:
    if (dict[i]<2):
        print(i,dict[i])
        break

Other method​

list = [1,2,3,5,2,1]
dict={}
for i in list:
    if list.count(i)==1:
        print(i)
        break

Calculate the count of Negative and Positive numbers in a list​

list = [1,2,3,4,-3,-45]
e=0
o=0
for i in list:
    if(i<0):
        e=e+1
    elif(i>0):
        o=o+1

print("POS",o)
print("NEG",e)

Find the no of repeating numbers​

# find no of repeating numbers from given number
i = int(input())
n=i
list=[]
dict={}
while (i>0):
    list.append(i%10)
    i=i//10
ctr=0
print(list)
for i in list:
    if i in dict:
        dict[i] += 1
    else:
        dict[i] = 1
print(dict)

for i,j in dict.items():
    if j>1:
        ctr=ctr+1
print(ctr)

Alternate method​


list1 = [4, 3, 2, 3, 2, 1]
seen = set()

for i in list1:
    if i not in seen:
        seen.add(i)

print(seen)
clone = list1.copy()
for i in seen:
        clone.remove(i)
print(len(clone))

Alternate method​

list1 = [4, 3, 2, 3, 2, 1]
cache = [0,0,0,0,0,0,0,0,0]
for i in range(len(list1)):
    cache[list1[i]]=cache[list1[i]]+1
print(cache)
ctr=0
for i in cache:
    if cache[i]>1:
        ctr=ctr+1
print(ctr)

Anagram(both str contains same letters)​

str1 = input()
str2 = input()

list1= list(str1)
list2= list(str2)
list1.sort()
list2.sort()
print(list1)
print(list2)
if(list1 == list2):
    print("Anagram")

Pangram (contains all letters)​

str = input()
seenAlpha= set()
strList= list(str.lower())
for i in strList:
    if i not in seenAlpha:
        seenAlpha.add(i)
print(seenAlpha)
if(len(seenAlpha)==27 or len(seenAlpha)==26):
    print("Y")
else:
    print("N")

Remove duplicates from String​

str = "Programming"
# seenAlpha= set()
strList= list(str.lower())
liststr=[]
for i in strList:
    if i not in liststr:

        liststr.append(i)

print("".join(liststr))

Count the frequency of substring

sub = "str"
ogstring = "stroriginalstring"
print(ogstring.count(sub))