Working with Lists and Dictionaries — NCERT Solutions

items() returns a view of all key-value pairs as tuples.

So the output is:

dict_items([('Assam', 'Guwahati'), ('Bihar', 'Patna'), ('Maharashtra', 'Mumbai'), ('Rajasthan', 'Jaipur')])

len(stateCapital) returns the number of key-value pairs in the dictionary.

There are 4 states in the dictionary, so the output is 4.

The membership operator in checks whether the given key is present in the dictionary.

"Maharashtra" is a key in stateCapital, so the result is True.

stateCapital.get("Assam") returns the value mapped to the key Assam in the dictionary. From the given dictionary, Assam → Guwahati, so the output is Guwahati.

del stateCapital["Assam"] removes the key-value pair for Assam from the dictionary. The remaining dictionary is {'Bihar': 'Patna', 'Maharashtra': 'Mumbai', 'Rajasthan': 'Jaipur'}.

# Program to find the number of times an element occurs in a list
myList = []
n = int(input("How many elements do you want to enter: "))

for i in range(n):
    myList.append(int(input("Enter element: ")))

element = int(input("Enter the element to be counted: "))
count = 0

for x in myList:
    if x == element:
        count += 1

print("Number of times", element, "occurs in the list is", count)

# Program to separate positive and negative numbers
myList = []
n = int(input("How many elements do you want to enter: "))

for i in range(n):
    myList.append(int(input("Enter element: ")))

positive = []
negative = []

for x in myList:
    if x > 0:
        positive.append(x)
    elif x < 0:
        negative.append(x)

print("Original list:", myList)
print("Positive numbers:", positive)
print("Negative numbers:", negative)

# Program to find the largest and second largest elements
myList = []
n = int(input("How many elements do you want to enter: "))

for i in range(n):
    myList.append(int(input("Enter element: ")))

myList.sort()
largest = myList[-1]
second_largest = myList[-2]

print("Largest element is:", largest)
print("Second largest element is:", second_largest)

# Program to find the median of a list
myList = []
n = int(input("How many elements do you want to enter: "))

for i in range(n):
    myList.append(int(input("Enter element: ")))

myList.sort()

if n % 2 == 1:
    median = myList[n // 2]
else:
    median = (myList[n // 2 - 1] + myList[n // 2]) / 2

print("Median is:", median)

# Program to remove duplicate elements from a list
myList = []
n = int(input("How many elements do you want to enter: "))

for i in range(n):
    myList.append(input("Enter element: "))

uniqueList = []
for x in myList:
    if x not in uniqueList:
        uniqueList.append(x)

print("List without duplicates:", uniqueList)

# Program to insert an element at a desired position
myList = []
n = int(input("How many elements do you want to enter: "))

for i in range(n):
    myList.append(int(input("Enter element: ")))

element = int(input("Enter the element to be inserted: "))
pos = int(input("Enter the position: "))
myList.insert(pos, element)

print("Updated list:", myList)

# Program to delete an element by its position
myList = []
n = int(input("How many elements do you want to enter: "))

for i in range(n):
    myList.append(int(input("Enter element: ")))

pos = int(input("Enter the position of the element to be deleted: "))
if pos < len(myList):
    deleted = myList.pop(pos)
    print("Deleted element is:", deleted)
    print("Updated list:", myList)
else:
    print("Position is out of range")

# Program to delete an element by its value
myList = []
n = int(input("How many elements do you want to enter: "))

for i in range(n):
    myList.append(int(input("Enter element: ")))

value = int(input("Enter the value of the element to be deleted: "))
if value in myList:
    myList.remove(value)
    print("Updated list:", myList)
else:
    print("Element is not present in the list")

# Program to find the highest 2 values in a dictionary
myDict = {'a': 10, 'b': 45, 'c': 32, 'd': 99, 'e': 67}

values = sorted(myDict.values(), reverse=True)

print("Highest value:", values[0])
print("Second highest value:", values[1])

# Program to create a dictionary from the string 'w3resource'
st = 'w3resource'
dic = {}

for i, ch in enumerate(st):
    if ch not in dic:
        dic[ch] = i

print(dic)

# Display the name and phone number for all friends
friends = {'Aman': '9876543210', 'Riya': '9123456780', 'Sohan': '9012345678'}

for name in friends:
    print(name, friends[name])

# Add a new key-value pair and display the modified dictionary
friends = {'Aman': '9876543210', 'Riya': '9123456780'}

friends['Sohan'] = '9012345678'
print(friends)

# Delete a particular friend from the dictionary
friends = {'Aman': '9876543210', 'Riya': '9123456780', 'Sohan': '9012345678'}

friend = input("Enter the friend to delete: ")
if friend in friends:
    del friends[friend]
    print(friends)
else:
    print("Friend not present")

# Modify the phone number of an existing friend
friends = {'Aman': '9876543210', 'Riya': '9123456780'}

friend = input("Enter the friend name: ")
if friend in friends:
    new_number = input("Enter the new phone number: ")
    friends[friend] = new_number
    print(friends)
else:
    print("Friend not present")

# Check if a friend is present in the dictionary or not
friends = {'Aman': '9876543210', 'Riya': '9123456780'}

friend = input("Enter the friend name: ")
if friend in friends:
    print("Friend is present")
else:
    print("Friend is not present")

# Display the dictionary in sorted order of names
friends = {'Riya': '9123456780', 'Aman': '9876543210', 'Sohan': '9012345678'}

for name in sorted(friends):
    print(name, friends[name])

# Program to store student details and perform required operations
students = {}
n = int(input("Enter the number of students: "))

for i in range(n):
    roll = input("Enter roll number: ")
    name = input("Enter name: ")
    percentage = float(input("Enter percentage: "))
    students[roll] = (name, percentage)

# Search a student by roll number
search_roll = input("Enter roll number to search: ")
if search_roll in students:
    print("Details:", search_roll, students[search_roll])
else:
    print("Student not found")

# Display all students
print("\nAll student results:")
for roll in students:
    print(roll, students[roll][0], students[roll][1])

# Find topper
max_roll = None
max_perc = -1
for roll in students:
    if students[roll][1] > max_perc:
        max_perc = students[roll][1]
        max_roll = roll

print("\nTopper:", max_roll, students[max_roll][0], students[max_roll][1])

# Subject toppers cannot be found from this data alone because only name and percentage are stored.
# To find subject toppers, marks in each subject must also be stored.